EP3208582A1 - Difference measuring circuit and a weighing apparatus with force compensation - Google Patents

Difference measuring circuit and a weighing apparatus with force compensation Download PDF

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Publication number
EP3208582A1
EP3208582A1 EP16156026.3A EP16156026A EP3208582A1 EP 3208582 A1 EP3208582 A1 EP 3208582A1 EP 16156026 A EP16156026 A EP 16156026A EP 3208582 A1 EP3208582 A1 EP 3208582A1
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EP
European Patent Office
Prior art keywords
signal
measuring circuit
ramp
int
node
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Granted
Application number
EP16156026.3A
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German (de)
French (fr)
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EP3208582B1 (en
Inventor
David Koller
Cyrill Bucher
Christoph Trautweiler
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Mettler Toledo Schweiz GmbH
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Mettler Toledo Schweiz GmbH
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Priority to PL16156026T priority Critical patent/PL3208582T3/en
Priority to EP16156026.3A priority patent/EP3208582B1/en
Priority to JP2017016818A priority patent/JP6810624B2/en
Priority to US15/434,276 priority patent/US10240968B2/en
Priority to CN201710085300.8A priority patent/CN107091676B/en
Publication of EP3208582A1 publication Critical patent/EP3208582A1/en
Application granted granted Critical
Publication of EP3208582B1 publication Critical patent/EP3208582B1/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01G—WEIGHING
    • G01G9/00—Methods of, or apparatus for, the determination of weight, not provided for in groups G01G1/00 - G01G7/00
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01G—WEIGHING
    • G01G7/00—Weighing apparatus wherein the balancing is effected by magnetic, electromagnetic, or electrostatic action, or by means not provided for in the preceding groups
    • G01G7/02—Weighing apparatus wherein the balancing is effected by magnetic, electromagnetic, or electrostatic action, or by means not provided for in the preceding groups by electromagnetic action
    • G01G7/04—Weighing apparatus wherein the balancing is effected by magnetic, electromagnetic, or electrostatic action, or by means not provided for in the preceding groups by electromagnetic action with means for regulating the current to solenoids
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01G—WEIGHING
    • G01G19/00—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups
    • G01G19/40—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight
    • G01G19/413—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight using electromechanical or electronic computing means
    • G01G19/414—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight using electromechanical or electronic computing means using electronic computing means only

Definitions

  • the invention relates to a differential measuring circuit for a balance with electromagnetic force compensation and a balance with electromagnetic force compensation.
  • a balance with electromagnetic force compensation which has a control device with a differential measuring circuit, is for example from [1], DE 101 53 603 A1 , known.
  • the balance described therein has, as in below Fig. 1 shown, a cup-shaped permanent magnet system 109 with an air gap in which a connected to a movable lever 106 coil 110 is arranged, which is traversed by a compensation current I com p, the size of which depends on the force acting on the measuring lever 106.
  • the position of the measuring lever 106 is measured by means of an opto-electrical measuring device 111, which is connected to a control device 10 ', which controls the compensation current I com p as a function of the supplied measuring signals such that the measuring lever 106 is always kept in the same position or after a Load change is returned.
  • the permanent magnet system 109 is arranged in a bracket 104, which is connected by means of flexure bearings 103 a via parallel guide arm 103 with a hanger 101, which has a serving for receiving a load to be measured boom 101 a.
  • the normal component of the load caused by a load is transmitted from the hanger 101 by a coupling 105 on the measuring lever 106, which is suspended by means of a flexure bearing 107 to a portion 104b of the console 104.
  • the optoelectrical measuring device 111 has two photodiodes D1, D2, which are arranged on the inside of an angle part 104a held by the console 104, opposite a light-emitting diode D3.
  • the photodiodes D1, D2 and the LED D3 projects as a diaphragm or slit and provided with a slot opening 106a tail 106b of the measuring lever 106 in such that emitted by the light emitting diode D3 radiation depending on the position of the diaphragm 106b through the Slit opening 106a can reach the photodiodes D1, D2, which the control device 10 'corresponding photocurrents I 1 and I 2 supply.
  • the control device 10 ' has a differential measuring circuit 1' , which forms a differential voltage u ⁇ based on the two currents I 1 and I 2 , which is equal to zero, when the photocurrents I 1 and I 2 are the same size.
  • the differential voltage u ⁇ is fed to a downstream driver circuit 2, which outputs a corresponding compensation current I comp via a reference resistor 3 to the coil 110, whereby a counterforce corresponding to the load is generated, which returns the measuring lever 106 to the starting position.
  • the voltage caused on the reference resistor 3 by the compensation current I comp is detected by a converter module A / D and converted into a corresponding digital value which is displayed on a display unit DSP.
  • differential measuring circuits which are suitable for forming a differential signal from two signals which are emitted by two photodiodes are, for example, from [2], US 3,727,708 A , as well as [3], DE 2 311 676 A , known.
  • a non-contact path-to-voltage converter having a differential diode photodiode made up of two single diodes which is connected through the slit of a slidable shutter, e.g. through the slot 106a provided in the end piece 106b of the measuring lever 106, optical radiation can be supplied.
  • the photodiodes and emitted photocurrents are in this circuit via a first and second operational amplifier, in which proportional to the photocurrents voltages are supplied to the inputs of a third operational amplifier, at whose output a difference signal is formed, which is proportional to the difference of the output voltages the first two operational amplifiers and is proportional to the displacement of the slit diaphragm.
  • a plurality of resistors and operational amplifiers are required in the differential measuring circuits described in [2] and [3], the temperature and operating behavior of which can unfavorably influence the resulting difference signal, which causes measurement errors in a balance with electromagnetic force compensation.
  • Operational amplifiers often have disturbing offset voltages which, like resistors, can experience disturbing deviations as a function of an often unstable ambient temperature.
  • a switch SW is so connected to the two photodiodes D1, D2 and the inverting input of a first operational amplifier OA ⁇ and periodically switched by a control unit CTRL between two states zt 1 , zt 2 , that during a first period portion t 1 in the first switching state z t1 the first photocurrent I 1 and during a second, equal period proportion t 2 in the second switching state zt 2 the second photocurrent I 2 via a first node K ⁇ the inverting input of the first operational amplifier OA ⁇ is supplied.
  • the first operational amplifier OA ⁇ whose output at which the output signal u ⁇ is formed, is connected by means of a parallel to a capacitor C ⁇ connected resistor R ⁇ with its inverting input and operates as a decelerating proportional controller.
  • a reference current I 0 is fed from a reference voltage source U 0 via a reference resistor R 0 to the inverting input of a second operational amplifier OA ⁇ , which is applied to a second node K ⁇ , so that depending on the difference of the photocurrents I 1 flowing during the first period component , I 2 and of the reference current I 0 flowing during the first and second period components, a sum voltage u ⁇ is formed at the output of the further operational amplifier OA ⁇ which is dependent on the magnitude of the reference current I 0 and the photocurrents I 1 , I 2 .
  • the second operational amplifier OA ⁇ whose output is connected by a capacitor C ⁇ to the inverting input, is connected as an integrator.
  • Electromagnetic force compensation scales such as those described above are well established.
  • the technology used is simple and efficient. Consequently, progress can only be made with considerable effort with this technology.
  • the present invention is therefore based on the object to provide an improved differential measuring circuit for a balance with electromagnetic force compensation and an improved balance with electromagnetic force compensation.
  • a differential measuring circuit to be created which is simple on the one hand and on the other hand quickly and reliably delivers a precise output signal.
  • the differential measuring circuit should work stably in all possible states, possibly switching states.
  • the individual components are to be operated with defined operating parameters which are not influenced by switching operations.
  • a simple symmetrical circuit structure is to be achieved, which is robust against acting disturbances.
  • Used photodiodes should be able to be operated constantly in an ideal work area.
  • the switching of the photocurrents, which may cause interference, should preferably be avoided.
  • an output signal is to be generated, which can advantageously be further processed.
  • the inventive balance with electromagnetic force compensation should allow to adapt cars to different applications, in particular to be able to better counteract disturbances occurring there and to further improve the measurement results.
  • the difference measuring circuit provided for use in a balance with electromagnetic force compensation, the photocurrents of which are supplied from two photodiodes and which is adapted to produce an output signal proportional to the difference of these photocurrents comprises a switch which is within two periods of a period between two states is switchable to affect the flow of current through a node to which the two photocurrents can be fed.
  • the switch can be controlled in such a way that a reference current emitted by a voltage or current source can be superimposed alternately within the period components on one of the two photocurrents permanently flowing to the node.
  • the node is located at the input of an integrator whose integrator signal is comparable in a comparator with a cyclic ramp signal having said period, wherein at the output of the comparator, a rectangular comparator signal can be generated, the duty cycle is defined by the intersection of the integrator signal and the ramp signal and which is a control input of the switch can be supplied.
  • the photocurrents are thus not switched on and off alternately, but both are permanently utilized, which is why the available information, which can use the position of a diaphragm through which light can reach the two photodiodes, can be used without loss.
  • the switch alternately superimposes a reference current on the two photocurrents. Within the first period component, the reference current is superimposed on the first photocurrent, and within the second period component, the reference current is superimposed on the second photocurrent.
  • the critical photocurrents themselves are not switched, but the uncritical reference current, which is why disturbances are avoided and the symmetry of the circuit is always maintained.
  • the difference measuring circuit according to the invention is so stable that no special reference current source is required for the supply of the reference current.
  • the reference current can flow through a reference resistor which is connected to the operating voltage of the circuit arrangement.
  • the electrodes of the photodiodes are not switched.
  • the cathodes of the photodiodes are connected to a common voltage potential, eg a stable operating voltage.
  • the photodiodes Conventionally, they can be connected in such a way that they operate in a preferred range of the characteristic curves and are optionally operated with a bias voltage.
  • the first electrode e.g. the anode of the first photodiode is connected directly to the node.
  • the first electrode or the anode of the second photodiode is connected to the node via an inverter in which the second photocurrent is inverted.
  • the second electrodes of the two photodiodes are connected to the common voltage potential.
  • the two photocurrents can be easily supplied to the node to form a differential current.
  • the inverter is arranged after the summation point at which the reference current is superimposed on the relevant photocurrent. That is, in the inverter, the sum of the reference current and the respective photocurrent is inverted.
  • the first electrode of the second photodiode in the inverter is connected to an inverting input of a first operational amplifier, the output of which is connected via a first resistor to the inverting input of the first operational amplifier and via an equal second resistor to the node.
  • a first operational amplifier the output of which is connected via a first resistor to the inverting input of the first operational amplifier and via an equal second resistor to the node.
  • the node to which the two photocurrents and each of the two photocurrents superimposed reference current is supplied, is located at the input of an integrator, at the output of an integrator signal is formed.
  • the differential current passing through the node is fed to the inverting input of a second operational amplifier connected as an integrator whose output is connected by a capacitor to the inverting input, which is charged or discharged by means of the differential current.
  • the integrator signal output by the integrator is compared in a comparator with a cyclically running ramp signal, which has the said period duration, which corresponds to the sum of the two period components.
  • the integrator signal is preferably fed to a first input of a third or a comparator-connected operational amplifier, at the second input of which the ramp signal is present, and at the output of which the preferably rectangular comparator signal is output.
  • the ramp signal is preferably generated by means of a first counter, which counts up within the period from an initial value to a final value and is then reset.
  • the digital output signal is converted in a ramp generator into a voltage corresponding thereto.
  • the ramp signal cycles through a voltage range within which the integrator signal lies. By means of the ramp signal can thus be determined to which point within the voltage range, the integrator signal has moved.
  • the output signal of the comparator is switched over. With the resetting of the ramp signal after the period has expired, the output signal of the comparator is also reset. At the output of the comparator thus results in a square wave whose duty cycle is dependent on the output signal of the integrator and thus the difference of the two photocurrents.
  • the comparator signal is a so-called pulse width modulated signal or a PWM signal.
  • the pulse-width modulated comparator signal is supplied to the control input of the switch, so that the reference current is superimposed alternately on the first and the second photocurrent as a function of the duty cycle of the comparator signal.
  • the pulse-width-modulated comparator signal is additionally used to return the diaphragm in each case to a starting position in which the light source, e.g. a light emitting diode, emitted light preferably reaches equal proportions to the two photodiodes.
  • the light source e.g. a light emitting diode
  • the balance with electromagnetic force compensation comprises a boom, from which a force to be measured can be transmitted via a coupling to a first end piece of a rotatably mounted measuring lever, the second end piece on the one hand a coil in a magnetic field and on the other hand holds the aperture, passes through the light from a light source to superposed photodiodes.
  • the photocurrents emitted by the photodiodes are fed as reference variables to the differential measuring circuit provided in a control device, from which the corresponding preferably pulse-width-modulated comparator signal or a corresponding analog feedback variable is fed to an analog controller or particularly preferably a digital feedback variable to a digital controller.
  • the period of the comparator signal, with which the photocurrents are switched over preferably counted by means of a first counter.
  • the target state of the duty cycle is 50/50, i. when a polarity change occurs at half the ramp height or in the middle of the period of the comparator signal. Since the difference in the period proportions is equal to zero in the target state of the duty cycle, the difference of the period proportions can thus also be regulated against this desired value or toward zero.
  • a digital feedback variable for example, the number of countersteps after occurrence of the polarity change until reaching the desired value or, if a deflection of the diaphragm in the other direction has been counted from the setpoint to the occurrence of the polarity change is counted with a second counter.
  • the second counter can therefore be formed from the difference of the period components t 1 , t 2 of the comparator signal or a part or multiple thereof or in another way from the duty cycle of the comparator signal, a digital quantity that is proportional to the position of the movable diaphragm.
  • the preferably digital controller which usually has a comparison element and a control element, calculates in this preferred embodiment of the invention as a result of a digital control variable, using which the reference variable is performed against the desired value.
  • the comparison element can be omitted in the present case, since the setpoint or the constant reference variable is equal to zero and the feedback variable supplied to the control element is equal to the control difference.
  • the control element which preferably operates as a PID controller, evaluates the control difference, ie the information as to whether, how and how far the controlled variable or the feedback variable deviates from the current setpoint, as an input variable and calculates a digital controller output variable, which is the control difference and corresponding to the weight change effected and thus superimposed on a stored digital manipulated variable corresponding to the weight measured before the weight change.
  • the updated digital manipulated variable is converted in a downstream D / A converter into a corresponding analog manipulated variable, for which a proportional compensation current is generated in a driver circuit and supplied to the coil.
  • the force to be measured is compensated and the measuring lever is returned to the initial position, in which the light from the light source passes through the diaphragm in equal parts to the two photodiodes. In this position the control difference becomes zero again.
  • the aperture When changing the weight on the balance of e.g. one percent, the aperture is shifted, resulting in a difference of the photocurrents, which is corrected by a change of the digital manipulated variable.
  • the manipulated variable If, for example, a weight of 1000 g on the weighing pan, the manipulated variable has e.g. the binary value 1111101000. With a deviation of 1% or with the increase of the weight by 10g, a corresponding control difference results and the controller in the configuration of a proportional controller calculates a digital controller output variable with the value 1010. Taking into account the determined digital controller output variable, the value becomes the manipulated variable thus increased and is after the weight change at 1111110010.
  • the controller is a computer in which an operating program is implemented, by means of which measurement processes can be controlled.
  • the digital manipulated variable is preferably calculated taking into account the controlled measuring process, wherein e.g. for an expected weight change of one percent, a change in the position size of 0.5% is made in advance and the digital control value of 1111101000 is set to 1111101101 and guided to the final value after the weight change has occurred.
  • filters can be set by means of which the digital measured variables are filtered.
  • the filter parameters can in turn take into account the expected Changes are selected so that filtering processes take little time or optimized waveforms result.
  • the controller is connected to at least one sensor, by means of which a disturbance variable is measured and the digital manipulated variable is calculated taking into account the interference that has occurred.
  • the controller is preferably provided with software routines that are provided for the treatment of the disorders in question.
  • the inventive balance with electromagnetic force compensation can thus be adapted to the environment and to measurement processes that influence the control process that optimal measurement results can be achieved.
  • Fig. 3a shows a differential measuring circuit 1 according to the invention, which in the balance with electromagnetic force compensation of Fig. 5 is used in a control device 10.
  • the differential measuring circuit 1 of Fig. 3a comprises two photodiodes D1, D2, to which light from a light source D3, preferably a light emitting diode, can be fed through an aperture 106a in a slidable aperture provided on a second end 106b of a rotatably mounted measuring lever 106, as already described with reference to FIG Fig. 1 has been described.
  • a light source D3 preferably a light emitting diode
  • the cathodes of the photodiodes D1 and D2 are permanently connected to a common voltage potential UB and not as in the circuit arrangement of Fig. 2a connected to a switch.
  • the photodiodes D1 and D2 can therefore be operated stably in a selected operating range.
  • a positive voltage potential U B or a positive bias voltage or reverse voltage is applied to the cathodes of the photodiodes D1 and D2, whereby the photodiodes D1 and D2 stop band are operated.
  • a first photocurrent I 1 is fed directly to a node K ⁇ .
  • a second photocurrent I 2 via an inverter INV the node K ⁇ fed directly.
  • the inverter INV the polarity of the second photocurrent I 2 is inverted, to which optionally a reference current I Ref2 is superimposed.
  • the second photocurrent I 2 is supplied to the inverting input of a first operational amplifier OA INV whose output is connected on the one hand via a first resistor R1 to the inverting input and on the other hand via a second resistor R2 to the node K ⁇ .
  • the second photocurrent I 2 flows through the first resistor R1, which is why over the first resistor R1 results in a voltage corresponding to the product I 2 * R1. Since both the first and second resistors R1, R2 are virtually grounded at one end, the same voltage potential results across the second resistor R2 as across the first resistor R1.
  • both resistors R1, R2 are the same size but with different ends to ground, flows in the resistor R2, the same current as in the resistor R1, but with the opposite sign.
  • the second photocurrent I 2 is therefore supplied to the node K ⁇ in reverse polarity.
  • a reference current I Ref1 is superimposed on the first photocurrent I 1 in a first period component t 1 in the position z t1 .
  • the reference current I Ref2 is superimposed on the second photocurrent I 2 .
  • the symbolically shown switching contact of the switch SW which is preferably designed as a semiconductor switch, is connected via a reference resistor R Ref with its own reference voltage U Ref .
  • the reference current I Ref therefore corresponds to the quotient U Ref / R Ref .
  • Both points at which the reference currents I Ref1 and I Ref2 are superimposed on the respective photocurrent I 1 and I 2 are virtually grounded, which is why in both positions of the switch SW the reference voltage U Ref is applied to the reference resistor R Ref and the two reference currents I Ref1 or I Ref2 are identical and can be simplified reference to a single reference current I Ref .
  • the node K ⁇ is located at the input of an integrator INT or at the inverting input of a second operational amplifier OA INT provided therein, whose Output is connected via a capacitor C INT to the node K ⁇ , which is why the difference currents occurring in the period components t 1 , t 2 inflow as integrator current I INT to the capacitor C INT and load or discharge this. If the currents cancel each other at the node K ⁇ , the charge of the capacitor C INT and its output signal or the integrator signal s INT at the output of the second operational amplifier OA INT remain unchanged.
  • this state is to be achieved as soon as the integrator signal SINT , at the time at which the integrator signal s INT and the ramp signal s RAMP intersect, is proportional to the deflection of the diaphragm and to the difference of the photocurrents I 1 , I 2 .
  • the integrator signal s INT is to be measured and compared with a reference signal and to generate a corresponding switching signal for the switch SW such that the differential current at the node K ⁇ becomes zero when the integrator signal s INT has reached a value, which is proportional to the deflection of the diaphragm.
  • the integrator signal s INT is supplied to a comparator CMP or in the non-inverting input of a third operational amplifier OA CMP, a ramp signal s RAMP is applied to the inverting input of which preferably corresponds to the voltage range which can be traversed by the integrator signal s INT.
  • the ramp signal s RAMP is generated by a ramp generator RG at whose input a counter signal of a first counter is applied.
  • the first counter Z1 counts up periodically, wherein the ramp generator RG generates a corresponding analog signal. After the period has expired, the first counter Z1 is reset and starts up again.
  • the comparator signal s PWM is subsequently supplied to the control input of the switch SW, so that the time periods t 1 , t 2 in which the reference current I Ref is superimposed on the photocurrents I 1 , I 2 are changed until at the node K ⁇ im Means a current difference of zero occurs and compensate for the capacitor C INT supplied and removed charges.
  • the comparator signal s PWM is also used to control the aperture, wherein in a second counter Z2 from the comparator signal s PWM a digital measurement or feedback variable s MG is derived, as described above.
  • the second Counter Z2 counts, for example, the number of steps after occurrence of the polarity change until reaching the desired value of the diaphragm or, if a deflection of the diaphragm in the other direction has taken place, from the setpoint to the occurrence of the polarity change.
  • the first and second counters Z1, Z2 are preferably contained in a common counter module Z.
  • the controller R D mentioned below is realized by means of a processor comprising a plurality of counters which are optionally programmable.
  • the determined digital measuring or feedback variable s MG is fed from the output of the differential measuring circuit 1 to the input of a digital controller R D. Since the reference variable d FG is preferably equal to zero and the measuring or feedback variable s MG thus forms the control deviation and is to be regulated to zero, this is supplied by a control element which calculates a corresponding digital manipulated variable d SG , by means of the aperture again is returned to the starting position. As has been explained above, the necessary change in the manipulated variable d SG is calculated in each case for a weight change, with which the diaphragm was previously guided to the starting position for a specific weight. The control variable determined by the controller R D is thus added to a stored control variable corresponding to the court, which was measured before the weight change.
  • Fig. 3b shows the differential measuring circuit 1 of Fig. 3a with the switch SW in a position in which the reference current I Ref2 or I Ref is superimposed on the second photocurrent I 2 .
  • the sum of the second photocurrent I 2 and the reference current I Ref is supplied to the inverter INV and output from this at the output inverted.
  • Fig. 4 shows waveforms of currents and signals that are within the differential measuring circuit 1 of Fig. 3a occur.
  • the curves of the reference currents I Ref1, I Ref2 are shown, which are superimposed on the first and the second photocurrent I 1 , I 2 by alternating actuation of the switch SW.
  • the third diagram shows the course of the integrator current I INT .
  • the fourth diagram shows the integrator signal s INT and the periodic and sawtooth ramp signal s RAMP .
  • the last diagram shows the rectangular and pulse-width-modulated comparator signal s CMP , which has rising edges when the ramp signal s RAMP drops and falling edges at the times at which the ramp signal s RAMP passes through the value integrator signal s INT .
  • Fig. 5 shows a scale according to the invention with electro-magnetic force compensation, which includes a control device 10, within the differential measuring circuit 1 of Fig. 3a the photocurrents I 1 and I 2 are supplied as controlled variables and from which a pulse-width-modulated signal s PWM is fed to a digital controller R D , which fulfills the tasks described above.
  • a control device 10 within the differential measuring circuit 1 of Fig. 3a the photocurrents I 1 and I 2 are supplied as controlled variables and from which a pulse-width-modulated signal s PWM is fed to a digital controller R D , which fulfills the tasks described above.
  • the extended processor-controlled controller R D determines the control deviation and determines a digital manipulated variable d SG , the is transmitted to a D / A converter 9, from which a corresponding analog manipulated variable a SG transmits to a driver circuit 2, which outputs a compensation current I com p to the compensation coil 110.
  • information is taken into account which can influence the measuring process and is not derived directly from a displacement of the diaphragm or a rotation of the measuring lever 106, but is supplied by further information sources.
  • Disturbances x can also influence the control process through movements of the material being measured. These movements of the material to be measured can in turn be detected by means of sensors 4 or reported by operating programs in the balance or in a control computer L.
  • the individual controller parameters are preferably controlled accordingly as a function of the aforementioned actions or disturbances.
  • PID Controllers are weighted according to the weighting factors, the P, I and D components when disturbances occur.
  • a control deviation can be introduced with foresight by means of which an expected weight change is compensated.
  • digital filters 5 can be used or their filter parameters can be changed in order to filter the signals processed in the digital controller R D.

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  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
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Abstract

Die für den Einsatz in einer Waage mit elektromagnetischer Kraftkompensation vorgesehene Differenzmessschaltung (1), der von zwei Fotodioden (D1, D2) abgegebene Fotoströme (I 1 , I 2 ) zuführbar sind und die geeignet ist, ein zur Differenz dieser Fotoströme (I 1 , I 2 ) proportionales Ausgangssignal zu erzeugen, umfasst einen Schalter (SW), der innerhalb von zwei Periodenanteilen t1, t2 einer Periodendauer T zwischen zwei Zuständen (z t1 , z t2 ) umschaltbar ist, um den Stromfluss durch einen Knotenpunkt (K –¡ ) zu beeinflussen, dem die beiden Fotoströme (I 1 , I 2 ) zuführbar sind. Erfindungsgemäss ist der Schalter (SW) derart steuerbar, dass ein von einer Spannungs- oder Stromquelle (U Ref ) abgegebener Referenzstrom (I Ref ) innerhalb der Periodenanteile t1, t2 alternierend einem der beiden Fotoströme (I 1 , I 2 ) überlagert wird, die dem Knotenpunkt (K –¡ ) permanent zufliessen. Der Knotenpunkt (K –¡ ) liegt am Eingang eines Integrators (INT), dessen Integratorsignal (s INT ) in einem Komparator (CMP) mit einem zyklisch verlaufenden Rampensignal (s RAMP ) vergleichbar ist, welches die Periodendauer T aufweist, wobei am Ausgang des Komparators (CMP) ein rechteckförmiges Komparatorsignal (s PWM ) erzeugbar ist, dessen Tastverhältnis durch den Schnittpunkt des Integratorsignal (s INT ) und des Rampensignals (s RAMP ) definiert ist und das einem Steuereingang des Schalters (SW) zuführbar ist.The differential measuring circuit (1) provided for use in a scale with electromagnetic force compensation, to which photocurrents (I 1 , I 2 ) emitted by two photodiodes (D1, D2) can be fed and which is suitable for generating a differential between these photocurrents (I 1 , I 2 ) proportional output signal comprises a switch (SW) which can be switched between two states (z t1 , z t2 ) within two period portions t1, t2 of a period duration T in order to switch the current flow through a node (K ¡ ) to influence the two photocurrents (I 1, I 2) can be fed. According to the invention, the switch (SW) can be controlled in such a way that a reference current (I Ref ) emitted by a voltage or current source (U Ref ) is alternately superimposed on one of the two photocurrents (I 1 , I 2 ) within the period components t1, t2 flow permanently to the node (K ¡ ). The node (K ¡ ) is at the input of an integrator (INT), whose integrator signal (s INT ) can be compared in a comparator (CMP) with a cyclically running ramp signal (s RAMP ), which has the period T, with the output of the Comparator (CMP), a square-wave comparator signal (s PWM) can be generated, the duty cycle of which is defined by the point of intersection of the integrator signal (s INT) and the ramp signal (s RAMP) and which can be fed to a control input of the switch (SW).

Description

Die Erfindung betrifft eine Differenzmessschaltung für eine Waage mit elektromagnetischer Kraftkompensation sowie eine Waage mit elektromagnetischer Kraftkompensation.The invention relates to a differential measuring circuit for a balance with electromagnetic force compensation and a balance with electromagnetic force compensation.

Eine Waage mit elektromagnetischer Kraftkompensation, welche eine Regeleinrichtung mit einer Differenzmessschaltung aufweist, ist z.B. aus [1], DE 101 53 603 A1 , bekannt. Die darin beschriebene Waage weist, wie nachstehend in Fig. 1 gezeigt, ein topfförmiges Permanentmagnetsystem 109 mit einem Luftspalt auf, in dem eine mit einem beweglichen Messhebel 106 verbundene Spule 110 angeordnet ist, die von einem Kompensationsstrom Icomp durchflossen wird, dessen Mass von der auf den Messhebel 106 einwirkenden Kraft abhängt. Die Lage des Messhebels 106 wird mittels einer opto-elektrischen Messvorrichtung 111 gemessen, die mit einer Regeleinrichtung 10' verbunden ist, welche den Kompensationsstrom Icomp in Abhängigkeit der zugeführten Messsignale derart regelt, dass der Messhebel 106 stets in gleicher Lage gehalten oder nach einer Laständerung zurückgeführt wird.A balance with electromagnetic force compensation, which has a control device with a differential measuring circuit, is for example from [1], DE 101 53 603 A1 , known. The balance described therein has, as in below Fig. 1 shown, a cup-shaped permanent magnet system 109 with an air gap in which a connected to a movable lever 106 coil 110 is arranged, which is traversed by a compensation current I com p, the size of which depends on the force acting on the measuring lever 106. The position of the measuring lever 106 is measured by means of an opto-electrical measuring device 111, which is connected to a control device 10 ', which controls the compensation current I com p as a function of the supplied measuring signals such that the measuring lever 106 is always kept in the same position or after a Load change is returned.

Das Permanentmagnetsystem 109 ist in einer Konsole 104 angeordnet, die mittels Biegelagern 103a über Parallelführungslenker 103 mit einem Gehänge 101 verbunden ist, das einen zur Aufnahme einer zu messenden Last dienenden Ausleger 101 a aufweist. Die Normalkomponente der von einer Last bewirkten Kraft wird vom Gehänge 101 durch eine Koppel 105 auf den Messhebel 106 übertragen, der mittels eines Biegelagers 107 an einem Teil 104b der Konsole 104 aufgehängt ist.The permanent magnet system 109 is arranged in a bracket 104, which is connected by means of flexure bearings 103 a via parallel guide arm 103 with a hanger 101, which has a serving for receiving a load to be measured boom 101 a. The normal component of the load caused by a load is transmitted from the hanger 101 by a coupling 105 on the measuring lever 106, which is suspended by means of a flexure bearing 107 to a portion 104b of the console 104.

Zur Messung der Position des Messhebels 106 weist die opto-elektrische Messvorrichtung 111 zwei Fotodioden D1, D2 auf, die auf der Innenseite eines von der Konsole 104 gehaltenen Winkelteils 104a einer Leuchtdiode D3 gegenüber angeordnet sind. In den Raum zwischen den Fotodioden D1, D2 und der Leuchtdiode D3 ragt ein als Blende oder Schlitzblende ausgebildetes und mit einer Schlitzöffnung 106a versehenes Endstück 106b des Messhebels 106 derart hinein, dass von der Leuchtdiode D3 abgegebene Strahlung abhängig von der Position der Blende 106b durch die Schlitzöffnung 106a zu den Fotodioden D1, D2 gelangen kann, welche der Regeleinrichtung 10' entsprechende Fotoströme I1 und I2 zuführen. Bei einer Drehung des Messhebels 106 aus seiner Ausgangslage oder Normallage gelangt dabei mehr Strahlung zur ersten oder zur zweiten Fotodiode D1, D2, weshalb unterschiedliche Fotoströme I1 und I2 über Anschlussleitungen 11, 12 zur Regeleinrichtung 10' gelangen.In order to measure the position of the measuring lever 106, the optoelectrical measuring device 111 has two photodiodes D1, D2, which are arranged on the inside of an angle part 104a held by the console 104, opposite a light-emitting diode D3. In the space between the photodiodes D1, D2 and the LED D3 projects as a diaphragm or slit and provided with a slot opening 106a tail 106b of the measuring lever 106 in such that emitted by the light emitting diode D3 radiation depending on the position of the diaphragm 106b through the Slit opening 106a can reach the photodiodes D1, D2, which the control device 10 'corresponding photocurrents I 1 and I 2 supply. Upon rotation of the measuring lever 106 from its starting position or normal position, more radiation reaches the first or the second photodiode D1, D2, which is why different photo currents I 1 and I 2 reach the control device 10 'via connecting lines 11, 12.

Die Regeleinrichtung 10' weist eine Differenzmessschaltung 1' auf, die anhand der beiden Ströme I1 und I2 eine Differenzspannung uΔ bildet, welche gleich Null wird, wenn die Fotoströme I1 und I2 gleich gross sind. Die Differenzspannung uΔ wird einer nachgeschalteten Treiberschaltung 2 zugeführt, die einen entsprechenden Kompensationsstrom Icomp über einen Referenzwiderstand 3 an die Spule 110 abgibt, wodurch eine zur Last korrespondierende Gegenkraft erzeugt wird, welche den Messhebel 106 in die Ausgangslage zurückführt. Die am Referenzwiderstand 3 durch den Kompensationsstrom Icomp verursachte Spannung wird von einem Wandlermodul A/D erfasst und in einen entsprechenden digitalen Wert gewandelt, der auf einer Anzeigeeinheit DSP angezeigt wird.The control device 10 'has a differential measuring circuit 1' , which forms a differential voltage u Δ based on the two currents I 1 and I 2 , which is equal to zero, when the photocurrents I 1 and I 2 are the same size. The differential voltage u Δ is fed to a downstream driver circuit 2, which outputs a corresponding compensation current I comp via a reference resistor 3 to the coil 110, whereby a counterforce corresponding to the load is generated, which returns the measuring lever 106 to the starting position. The voltage caused on the reference resistor 3 by the compensation current I comp is detected by a converter module A / D and converted into a corresponding digital value which is displayed on a display unit DSP.

Weitere Differenzmessschaltungen, die zur Bildung eines Differenzsignals aus zwei Signalen geeignet sind, die von zwei Fotodioden abgegeben werden, sind z.B. aus [2], US 3,727,708 A , sowie [3], DE 2 311 676 A , bekannt.Further differential measuring circuits which are suitable for forming a differential signal from two signals which are emitted by two photodiodes are, for example, from [2], US 3,727,708 A , as well as [3], DE 2 311 676 A , known.

In [3] ist ein berührungslos arbeitender Weg-Spannungswandler mit einer aus zwei Einzeldioden bestehenden Differential-Fotodiode beschrieben, der durch den Schlitz einer verschiebbaren Blende, z.B. durch den im Endstück 106b des Messhebels 106 vorgesehenen Schlitz 106a, optische Strahlung zuführbar ist. Die von den Fotodioden und abgegebenen Fotoströme werden bei dieser Schaltungsanordnung über einen ersten bzw. zweiten Operationsverstärker, in denen zu den Fotoströmen proportionale Spannungen gebildet werden, den Eingängen eines dritten Operationsverstärkers zugeführt, an dessen Ausgang ein Differenzsignal gebildet wird, das proportional zur Differenz der Ausgangsspannungen der ersten beiden Operationsverstärker und proportional zum Verschiebeweg der Schlitzblende ist.In [3] there is described a non-contact path-to-voltage converter having a differential diode photodiode made up of two single diodes which is connected through the slit of a slidable shutter, e.g. through the slot 106a provided in the end piece 106b of the measuring lever 106, optical radiation can be supplied. The photodiodes and emitted photocurrents are in this circuit via a first and second operational amplifier, in which proportional to the photocurrents voltages are supplied to the inputs of a third operational amplifier, at whose output a difference signal is formed, which is proportional to the difference of the output voltages the first two operational amplifiers and is proportional to the displacement of the slit diaphragm.

Zur Bildung des Differenzsignals werden in den in [2] und [3] beschriebenen Differenzmessschaltungen mehrere Widerstände und Operationsverstärker benötigt, deren Temperatur- und Betriebsverhalten das resultierende Differenzsignal ungünstig beeinflussen können, wodurch in einer Waage mit elektromagnetischer Kraftkompensation Messfehler verursacht werden. Operationsverstärker weisen oft störende Offsetspannungen auf, welche, wie Widerstände, in Abhängigkeit einer oft nicht stabilen Umgebungstemperatur störende Abweichungen erfahren können.In order to form the differential signal, a plurality of resistors and operational amplifiers are required in the differential measuring circuits described in [2] and [3], the temperature and operating behavior of which can unfavorably influence the resulting difference signal, which causes measurement errors in a balance with electromagnetic force compensation. Operational amplifiers often have disturbing offset voltages which, like resistors, can experience disturbing deviations as a function of an often unstable ambient temperature.

Zur Vermeidung der Nachteile der in [2] und [3] offenbarten Schaltungsanordnungen wurde in [1] die nachstehend in den Figuren 2a und 2b gezeigte Differenzmessschaltung 1' vorgeschlagen, der von zwei Fotodioden D1, D2 abgegebene Fotoströme I1, I2 zuführbar sind. Die Differenzmessschaltung 1' bildet ein zur Differenz der Fotoströme I1, I2 proportionales Ausgangssignal uΔ, das weitgehend unabhängig von Schwankungen der Umgebungstemperatur ist. Dazu ist ein Schalter SW derart mit den beiden Fotodioden D1, D2 und dem invertierenden Eingang eines ersten Operationsverstärkers OAΔ verbunden und von einer Steuereinheit CTRL zwischen zwei Zuständen zt1, zt2 periodisch umschaltbar, dass während eines ersten Periodenanteils t1 im ersten Schaltzustand zt1 der erste Fotostrom I1 und während eines zweiten, gleich grossen Periodenanteils t2 im zweiten Schaltzustand zt2 der zweite Fotostrom I2 über einen ersten Knotenpunkt KΔ dem invertierenden Eingang des ersten Operationsverstärkers OAΔ zugeführt wird. Der erste Operationsverstärker OAΔ, dessen Ausgang, an dem das Ausgangssignal uΔ gebildet wird, ist mittels eines parallel zu einem Kondensator CΔ geschalteten Widerstandes RΔ mit dessen invertierendem Eingang verbunden und arbeitet als verzögernder Proportional-Regler.In order to avoid the drawbacks of the circuit arrangements disclosed in [2] and [3], in [1] the following have been described in FIGS FIGS. 2a and 2 B shown difference measuring circuit 1 'proposed, the output of two photodiodes D1, D2 photocurrents I 1 , I 2 can be fed. The differential measuring circuit 1 'forms to the difference of the photocurrents I 1 , I 2 proportional output signal u Δ , which is largely independent of fluctuations in the ambient temperature. For this purpose, a switch SW is so connected to the two photodiodes D1, D2 and the inverting input of a first operational amplifier OA Δ and periodically switched by a control unit CTRL between two states zt 1 , zt 2 , that during a first period portion t 1 in the first switching state z t1 the first photocurrent I 1 and during a second, equal period proportion t 2 in the second switching state zt 2 the second photocurrent I 2 via a first node K Δ the inverting input of the first operational amplifier OA Δ is supplied. The first operational amplifier OA Δ , whose output at which the output signal u Δ is formed, is connected by means of a parallel to a capacitor C Δ connected resistor R Δ with its inverting input and operates as a decelerating proportional controller.

Dem invertierenden Eingang eines zweiten Operationsverstärkers OA∑, der an einem zweiten Knotenpunkt K∑ anliegt, wird von einer Referenzspannungsquelle U0 über einen Referenzwiderstand R0 ein Referenzstrom I0 zugeführt, so dass in Abhängigkeit der Differenz der während des ersten Periodenanteils fliessenden Fotoströme I1, I2 und des während des ersten und des zweiten Periodenanteils fliessenden Referenzstromes I0 am Ausgang des weiteren Operationsverstärkers OA∑ eine Summenspannung u∑ gebildet wird, die abhängig von der Grösse des Referenzstroms I0 und der Fotoströme I1, I2 ist. Der zweite Operationsverstärker OA∑, dessen Ausgang durch einen Kondensator C∑ mit dem invertierenden Eingang verbunden ist, ist als Integrator beschaltet. Durch Regelung der Betriebsspannung der Leuchtdiode D3 in Abhängigkeit der Summenspannung u∑ werden die Fotoströme I1, I2 konstant gehalten.A reference current I 0 is fed from a reference voltage source U 0 via a reference resistor R 0 to the inverting input of a second operational amplifier OA Σ , which is applied to a second node K Σ , so that depending on the difference of the photocurrents I 1 flowing during the first period component , I 2 and of the reference current I 0 flowing during the first and second period components, a sum voltage u Σ is formed at the output of the further operational amplifier OA Σ which is dependent on the magnitude of the reference current I 0 and the photocurrents I 1 , I 2 . The second operational amplifier OA Σ , whose output is connected by a capacitor C Σ to the inverting input, is connected as an integrator. By controlling the operating voltage of the light emitting diode D3 as a function of the sum voltage u Σ , the photocurrents I 1 , I 2 are kept constant.

Die in [1] offenbarte Schaltungsanordnung, die relativ einfach aufgebaut ist, sieht somit vor, dass die Fotoströme I1, I2 sequenziell an die Differenzmessschaltung 1' angelegt werden, weshalb die Differenzbildung mit einer entsprechenden Verzögerung erfolgt und die Information des nicht angelegten Fotostromes I1 oder I2 jeweils verloren geht. Ferner erfolgt eine Verzögerung durch den ersten Operationsverstärker OAΔ, der als verzögernder Proportional-Regler arbeitet. Weiterhin ist die Spannung an den Kathoden der Fotodioden D1, D2 nicht definiert und ändert möglicherweise beim Umschalten des Schalters SW. Die Symmetrie der Schaltung, bei der der erste Fotostrom 11 die virtuelle Masse am invertierenden Eingang des zweiten Operationsverstärkers OA∑ durchfliesst, während der zweite Fotostrom I2 die tatsächliche Masse an der Anode der zweiten Fotodiode D2 durchfliesst, ist nicht gewährleistet.The circuit arrangement disclosed in [1], which is of relatively simple design, thus provides that the photocurrents I 1 , I 2 are applied sequentially to the differential measuring circuit 1 ', for which reason the difference is formed with a corresponding delay and the information of the non-applied photocurrent I 1 or I 2 is lost in each case. Furthermore, there is a delay through the first operational amplifier OA Δ , which operates as a decelerating proportional controller. Furthermore, the voltage at the cathodes of the photodiodes D1, D2 is undefined and may change upon switching of the switch SW. The symmetry of the circuit in which the first photocurrent 11 flows through the virtual ground at the inverting input of the second operational amplifier OA Σ , while the second photocurrent I 2 flows through the actual ground at the anode of the second photodiode D2 is not guaranteed.

Waagen mit elektromagnetischer Kraftkompensation, wie sie oben beschrieben wurden, sind weitgehend ausgereift. Die angewendete Technologie ist einfach und effizient. Konsequenterweise lassen sich mit dieser Technologie hingegen Fortschritte nur noch mit erheblichem Aufwand erzielen.Electromagnetic force compensation scales such as those described above are well established. The technology used is simple and efficient. Consequently, progress can only be made with considerable effort with this technology.

Der vorliegenden Erfindung liegt daher die Aufgabe zugrunde, eine verbesserte Differenzmessschaltung für eine Waage mit elektromagnetischer Kraftkompensation sowie eine verbesserte Waage mit elektromagnetischer Kraftkompensation zu schaffen.The present invention is therefore based on the object to provide an improved differential measuring circuit for a balance with electromagnetic force compensation and an improved balance with electromagnetic force compensation.

Insbesondere soll eine Differenzmessschaltung geschaffen werden, die einerseits einfach aufgebaut ist und andererseits rasch und zuverlässig ein präzises Ausgangssignal liefert.In particular, a differential measuring circuit to be created, which is simple on the one hand and on the other hand quickly and reliably delivers a precise output signal.

Die Differenzmessschaltung soll in allen möglichen Zuständen, ggf. Schaltzuständen stabil arbeiten. Die einzelnen Bauteile sollen mit definierten Betriebsparametern betrieben werden, die von Schaltvorgängen nicht beeinflusst sind. Mittels der Erfindung soll ein einfacher symmetrischer Schaltungssaufbau erzielt werden, der robust gegen einwirkende Störungen ist.The differential measuring circuit should work stably in all possible states, possibly switching states. The individual components are to be operated with defined operating parameters which are not influenced by switching operations. By means of the invention, a simple symmetrical circuit structure is to be achieved, which is robust against acting disturbances.

Verwendete Fotodioden sollen konstant in einem idealen Arbeitsbereich betrieben werden können. Die Umschaltung der Fotoströme, die Störungen verursachen kann, soll vorzugsweise vermieden werden.Used photodiodes should be able to be operated constantly in an ideal work area. The switching of the photocurrents, which may cause interference, should preferably be avoided.

Ein Verlust von Informationen bei der Auswertung der Messsignale soll vermieden werden.A loss of information in the evaluation of the measured signals should be avoided.

Ferner soll ein Ausgangssignal erzeugt werden, welches vorteilhaft weiter verarbeitet werden kann.Furthermore, an output signal is to be generated, which can advantageously be further processed.

Die erfindungsgemässe Waage mit elektromagnetischer Kraftkompensation soll es erlauben, Wagen an unterschiedliche Anwendungsgebiete zu adaptieren, insbesondere um dort auftretende Störungen besser begegnen zu können und die Messergebnisse weiter zu verbessern.The inventive balance with electromagnetic force compensation should allow to adapt cars to different applications, in particular to be able to better counteract disturbances occurring there and to further improve the measurement results.

Diese Aufgaben werden mit einer Differenzmessschaltung für eine Waage mit elektromagnetischer Kraftkompensation sowie mit einer Waage mit elektromagnetischer Kraftkompensation gelöst, welche die in Anspruch 1 bzw. 12 angegebenen Merkmale aufweisen. Vorteilhafte Ausgestaltungen der Erfindung sind in weiteren Ansprüchen angegeben.These objects are achieved with a differential measuring circuit for a balance with electromagnetic force compensation and with a balance with electromagnetic force compensation, which have the features specified in claim 1 or 12 features. Advantageous embodiments of the invention are specified in further claims.

Die für den Einsatz in einer Waage mit elektromagnetischer Kraftkompensation vorgesehene Differenzmessschaltung, der von zwei Fotodioden abgegebene Fotoströme zuführbar sind und die geeignet ist, ein zur Differenz dieser Fotoströme proportionales Ausgangssignal zu erzeugen, umfasst einen Schalter, der innerhalb von zwei Periodenanteilen einer Periodendauer zwischen zwei Zuständen umschaltbar ist, um den Stromfluss durch einen Knotenpunkt zu beeinflussen, dem die beiden Fotoströme zuführbar sind.The difference measuring circuit provided for use in a balance with electromagnetic force compensation, the photocurrents of which are supplied from two photodiodes and which is adapted to produce an output signal proportional to the difference of these photocurrents comprises a switch which is within two periods of a period between two states is switchable to affect the flow of current through a node to which the two photocurrents can be fed.

Erfindungsgemäss ist der Schalter derart steuerbar, dass ein von einer Spannungs- oder Stromquelle abgegebener Referenzstrom innerhalb der Periodenanteile alternierend einem der beiden Fotoströme überlagerbar ist, die dem Knotenpunkt permanent zufliessen. Der Knotenpunkt liegt am Eingang eines Integrators, dessen Integratorsignal in einem Komparator mit einem zyklisch verlaufenden Rampensignal vergleichbar ist, welches die genannte Periodendauer aufweist, wobei am Ausgang des Komparators ein rechteckförmiges Komparatorsignal erzeugbar ist, dessen Tastverhältnis durch den Schnittpunkt des Integratorsignal und des Rampensignals definiert ist und das einem Steuereingang des Schalters zuführbar ist.According to the invention, the switch can be controlled in such a way that a reference current emitted by a voltage or current source can be superimposed alternately within the period components on one of the two photocurrents permanently flowing to the node. The node is located at the input of an integrator whose integrator signal is comparable in a comparator with a cyclic ramp signal having said period, wherein at the output of the comparator, a rectangular comparator signal can be generated, the duty cycle is defined by the intersection of the integrator signal and the ramp signal and which is a control input of the switch can be supplied.

Erfindungsgemäss werden die Fotoströme somit nicht alternierend zu- und abgeschaltet, sondern beide permanent verwertet, weshalb die zur Verfügung stehende Information, welche die Position einer Blende, durch die hindurch Licht zu den beiden Fotodioden gelangen kann, ohne Verlust genutzt werden kann.According to the invention, the photocurrents are thus not switched on and off alternately, but both are permanently utilized, which is why the available information, which can use the position of a diaphragm through which light can reach the two photodiodes, can be used without loss.

Durch den Schalter wird den beiden Fotoströmen alternierend ein Referenzstrom überlagert. Innerhalb des ersten Periodenanteils wird dem ersten Fotostrom der Referenzstrom überlagert und innerhalb des zweiten Periodenanteils wird dem zweiten Fotostrom der Referenzstrom überlagert. Die kritischen Fotoströme selbst werden nicht geschaltet, sondern der unkritische Referenzstrom, weshalb Störungen vermieden werden und die Symmetrie der Schaltung stets gewahrt bleibt.The switch alternately superimposes a reference current on the two photocurrents. Within the first period component, the reference current is superimposed on the first photocurrent, and within the second period component, the reference current is superimposed on the second photocurrent. The critical photocurrents themselves are not switched, but the uncritical reference current, which is why disturbances are avoided and the symmetry of the circuit is always maintained.

Die erfindungsgemässe Differenzmessschaltung ist derart stabil, dass für die Lieferung des Referenzstroms keine besondere Referenzstromquelle erforderlich ist. Vorteilhaft kann der Referenzstrom durch einen Referenzwiderstand fliessen, der mit der Betriebsspannung der Schaltungsanordnung verbunden ist.The difference measuring circuit according to the invention is so stable that no special reference current source is required for the supply of the reference current. Advantageously, the reference current can flow through a reference resistor which is connected to the operating voltage of the circuit arrangement.

Vorteilhaft ist ferner, dass die Elektroden der Fotodioden nicht geschaltet werden. Stattdessen sind z.B. die Kathoden der Fotodioden mit einem gemeinsamen Spannungspotenzial, z.B. einer stabilen Betriebsspannung verbunden. Die Fotodioden können konventionell derart beschaltet werden, dass sie in einem bevorzugten Bereich der Kennlinien arbeiten und gegebenenfalls mit einer Vorspannung betrieben werden.It is also advantageous that the electrodes of the photodiodes are not switched. Instead, for example, the cathodes of the photodiodes are connected to a common voltage potential, eg a stable operating voltage. The photodiodes Conventionally, they can be connected in such a way that they operate in a preferred range of the characteristic curves and are optionally operated with a bias voltage.

In einer vorzugsweisen Ausgestaltung ist die erste Elektrode, z.B. die Anode der ersten Fotodiode direkt mit dem Knotenpunkt verbunden. Die erste Elektrode bzw. die Anode der zweiten Fotodiode ist hingegen über einen Inverter, in dem der zweite Fotostrom invertiert wird, mit dem Knotenpunkt verbunden. Die zweiten Elektroden der beiden Fotodioden sind hingegen mit dem gemeinsamen Spannungspotenzial verbunden.In a preferred embodiment, the first electrode, e.g. the anode of the first photodiode is connected directly to the node. By contrast, the first electrode or the anode of the second photodiode is connected to the node via an inverter in which the second photocurrent is inverted. The second electrodes of the two photodiodes, however, are connected to the common voltage potential.

Nach der Invertierung eines Fotostroms können die beiden Fotoströme zur Bildung eines Differenzstroms in einfacher Weise dem Knotenpunkt zugeführt werden. Der Inverter ist dabei nach dem Summationspunkt angeordnet, an dem der Referenzstrom dem betreffenden Fotostrom überlagert wird. D.h., im Inverter wird die Summe des Referenzstroms und des betreffenden Fotostroms invertiert.After the inversion of a photocurrent, the two photocurrents can be easily supplied to the node to form a differential current. The inverter is arranged after the summation point at which the reference current is superimposed on the relevant photocurrent. That is, in the inverter, the sum of the reference current and the respective photocurrent is inverted.

Vorzugsweise ist die erste Elektrode der zweiten Fotodiode im Inverter mit einem invertierenden Eingang eines ersten Operationsverstärkers verbunden, dessen Ausgang über einen ersten Widerstand mit dem invertierenden Eingang des ersten Operationsverstärker und über einen gleich grossen zweiten Widerstand mit dem Knotenpunkt verbunden ist. Durch die Wahl identischer Widerstände wird ein identischer Strom mit umgekehrter Polarität erzeugt.Preferably, the first electrode of the second photodiode in the inverter is connected to an inverting input of a first operational amplifier, the output of which is connected via a first resistor to the inverting input of the first operational amplifier and via an equal second resistor to the node. By choosing identical resistors, an identical current with reversed polarity is generated.

Der Knotenpunkt, dem die beiden Fotoströme sowie der jeweils einem der beiden Fotoströme überlagerte Referenzstrom zugeführt werden, liegt am Eingang eines Integrators, an dessen Ausgang ein Integratorsignal gebildet wird. Der den Knotenpunkt durchlaufende Differenzstrom wird in einer bevorzugten Ausgestaltung dem invertierenden Eingang eines als Integrator beschalteten zweiten Operationsverstärkers zugeführt, dessen Ausgang durch einen Kondensator mit dem invertierenden Eingang verbunden ist, der mittels des Differenstroms geladen oder entladen wird.The node to which the two photocurrents and each of the two photocurrents superimposed reference current is supplied, is located at the input of an integrator, at the output of an integrator signal is formed. In a preferred embodiment, the differential current passing through the node is fed to the inverting input of a second operational amplifier connected as an integrator whose output is connected by a capacitor to the inverting input, which is charged or discharged by means of the differential current.

Das vom Integrator abgegebene Integratorsignal wird in einem Komparator mit einem zyklisch verlaufenden Rampensignal verglichen, welches die genannte Periodendauer aufweist, die der Summe der beiden Periodenanteile entspricht. Das Integratorsignal wird vorzugsweise einem ersten Eingang eines dritten bzw. eines als Komparator beschalteten Operationsverstärkers zugeführt, an dessen zweitem Eingang das Rampensignal anliegt, und an dessen Ausgang das vorzugsweise rechteckförmige Komparatorsignal abgegeben wird.The integrator signal output by the integrator is compared in a comparator with a cyclically running ramp signal, which has the said period duration, which corresponds to the sum of the two period components. The integrator signal is preferably fed to a first input of a third or a comparator-connected operational amplifier, at the second input of which the ramp signal is present, and at the output of which the preferably rectangular comparator signal is output.

Das Rampensignal wird vorzugsweise mittels eines ersten Zählers erzeugt, der innerhalb der Periodendauer von einem Anfangswert bis zu einem Endwert hochzählt und dann zurückgesetzt wird. Das digitale Ausgangssignal wird in einem Rampengenerator in eine dazu korrespondierende Spannung gewandelt. Das Rampensignal durchläuft zyklisch einen Spannungsbereich, innerhalb dessen das Integratorsignal liegt. Mittels des Rampensignals kann somit festgestellt werden, zu welchem Punkt innerhalb des Spannungsbereichs sich das Integratorsignal bewegt hat. Jeweils bei Erreichen des Schnittpunktes zwischen dem Integratorsignal und dem Rampensignal wird das Ausgangssignal des Komparators umgeschaltet. Mit dem Zurücksetzen des Rampensignals nach Ablauf der Periodendauer wird auch das Ausgangssignal des Komparators wieder zurückgesetzt. Am Ausgang des Komparators resultiert somit ein Rechtecksignal, dessen Tastverhältnis abhängig ist vom Ausgangssignal des Integrators und somit der Differenz der beiden Fotoströme. Das Komparatorsignal ist ein sogenanntes pulsweitenmoduliertes Signal bzw. ein PWM-Signal.The ramp signal is preferably generated by means of a first counter, which counts up within the period from an initial value to a final value and is then reset. The digital output signal is converted in a ramp generator into a voltage corresponding thereto. The ramp signal cycles through a voltage range within which the integrator signal lies. By means of the ramp signal can thus be determined to which point within the voltage range, the integrator signal has moved. Each time the point of intersection between the integrator signal and the ramp signal is reached, the output signal of the comparator is switched over. With the resetting of the ramp signal after the period has expired, the output signal of the comparator is also reset. At the output of the comparator thus results in a square wave whose duty cycle is dependent on the output signal of the integrator and thus the difference of the two photocurrents. The comparator signal is a so-called pulse width modulated signal or a PWM signal.

Das pulsweitenmodulierte Komparatorsignal wird dem Steuereingang des Schalters zugeführt, sodass der Referenzstrom in Abhängigkeit des Tastverhältnisses des Komparatorsignals alternierend dem ersten und dem zweiten Fotostrom überlagert wird. Sobald das Integratorsignal, zum Zeitpunkt, an dem sich das Integratorsignal und das Rampensignal schneiden, proportional zur Differenz der Fotoströme ist, wird ein Tastverhältnis erreicht, welches bewirkt, dass sich die Summe des ersten Fotostroms und des während der ersten Zeitperiode zugeschalteten Referenzstroms einerseits und die Summe des zweiten Fotostroms und des während der zweiten Zeitperiode zugeschalteten Referenzstroms andererseits vollständig kompensieren. Sofern die mit dem Messhebel der Waage verbundene Blende nicht weiter bewegt wird, bleibt auch das Integratorsignal unverändert.The pulse-width modulated comparator signal is supplied to the control input of the switch, so that the reference current is superimposed alternately on the first and the second photocurrent as a function of the duty cycle of the comparator signal. Once the integrator signal, at the time the integrator signal and the ramp signal intersect, is proportional to the photocurrent difference, a duty cycle is achieved which causes the sum of the first photocurrent and the reference current applied during the first period of time to be the one On the other hand, to completely compensate for the sum of the second photocurrent and the reference current connected during the second time period. If the aperture connected to the scale lever is not moved, the integrator signal will remain unchanged.

In einer erfindungsgemässen Waage mit elektromagnetischer Kraftkompensation wird das pulsweitenmodulierte Komparatorsignal hingegen zusätzlich dazu verwendet, die Blende jeweils in eine Ausgangslage zurückzuführen, in der das von der Lichtquelle, z.B. einer Leuchtdiode, abgegebene Licht vorzugsweise zu gleichen Anteilen zu den beiden Fotodioden gelangt.In contrast, in a balance according to the invention with electromagnetic force compensation, the pulse-width-modulated comparator signal is additionally used to return the diaphragm in each case to a starting position in which the light source, e.g. a light emitting diode, emitted light preferably reaches equal proportions to the two photodiodes.

Die Waage mit elektromagnetischer Kraftkompensation umfasst einen Ausleger, von dem eine zu messende Kraft über eine Koppel auf ein erstes Endstück eines drehbar gelagerten Messhebels übertragbar ist, dessen zweites Endstück einerseits eine Spule in einem Magnetfeld und andererseits die Blende hält, durch die Licht von einer Lichtquelle zu übereinander angeordneten Fotodioden gelangt.The balance with electromagnetic force compensation comprises a boom, from which a force to be measured can be transmitted via a coupling to a first end piece of a rotatably mounted measuring lever, the second end piece on the one hand a coil in a magnetic field and on the other hand holds the aperture, passes through the light from a light source to superposed photodiodes.

Die von den Fotodioden abgegebenen Fotoströme werden als Führungsgrössen zu der in einer Regeleinrichtung vorgesehenen Differenzmessschaltung geführt, von der das dazu korrespondierende vorzugsweise pulsweitenmodulierte Komparatorsignal bzw. eine dazu korrespondierende analoge Rückführgrösse einem analogen Regler oder besonders bevorzugt eine digitale Rückführgrösse einem digitalen Regler zugeführt wird.The photocurrents emitted by the photodiodes are fed as reference variables to the differential measuring circuit provided in a control device, from which the corresponding preferably pulse-width-modulated comparator signal or a corresponding analog feedback variable is fed to an analog controller or particularly preferably a digital feedback variable to a digital controller.

Wie erwähnt wird die Periodendauer des Komparatorsignals, mit dem die Fotoströme umgeschaltet werden, vorzugsweise mittels eines ersten Zählers abgezählt. Der Sollzustand des Tastverhältnisses liegt bei 50/50, d.h. beim Auftritt eines Polaritätswechsels auf halber Rampenhöhe oder in der Mitte der Periodendauer des Komparatorsignals. Da beim Sollzustand des Tastverhältnisses die Differenz der Periodenanteile gleich Null ist, kann somit auch die Differenz der Periodenanteile gegen diesen Sollwert bzw. gegen Null geregelt werden.As mentioned, the period of the comparator signal, with which the photocurrents are switched over, preferably counted by means of a first counter. The target state of the duty cycle is 50/50, i. when a polarity change occurs at half the ramp height or in the middle of the period of the comparator signal. Since the difference in the period proportions is equal to zero in the target state of the duty cycle, the difference of the period proportions can thus also be regulated against this desired value or toward zero.

Da die Blende und somit das Komparatorsignal stets in den Sollzustand zurückgeführt werden sollen, bildet die Abweichung von diesem Sollzustand die gesuchte Führungsgrösse.Since the diaphragm and thus the comparator signal are always to be returned to the desired state, the deviation from this desired state forms the desired reference variable.

Zur Bildung einer digitalen Rückführgrösse wird z.B. mit einem zweiten Zähler die Anzahl Zählerschritte nach Auftreten des Polaritätswechsels bis zum Erreichen des Sollwerts oder, sofern eine Auslenkung der Blende in die andere Richtung erfolgt ist, vom Sollwert bis zum Auftreten des Polaritätswechsels gezählt. Mittels des zweiten Zählers kann daher aus der Differenz der Periodenanteile t1, t2 des Komparatorsignal aus oder einem Teil oder Mehrfachen davon oder auf andere Weise aus dem Tastverhältnis des Komparatorsignals eine digitale Messgrösse gebildet werden, die proportional zur Position der verschiebbaren Blende ist.To form a digital feedback variable, for example, the number of countersteps after occurrence of the polarity change until reaching the desired value or, if a deflection of the diaphragm in the other direction has been counted from the setpoint to the occurrence of the polarity change is counted with a second counter. By means of the second counter can therefore be formed from the difference of the period components t 1 , t 2 of the comparator signal or a part or multiple thereof or in another way from the duty cycle of the comparator signal, a digital quantity that is proportional to the position of the movable diaphragm.

Der vorzugsweise digitale Regler, der üblicherweise ein Vergleichsglied und ein Regelglied aufweist, berechnet bei dieser vorzugsweisen Ausgestaltung der Erfindung in der Folge eine digitale Stellgrösse, unter Anwendung derer die Führungsgrösse gegen den Sollwert geführt wird. Das Vergleichsglied kann im vorliegenden Fall entfallen, da der Sollwert bzw. die konstante Führungsgrösse gleich Null ist und die dem Regelglied zugeführte Rückführungsgrösse gleich der Regeldifferenz ist.The preferably digital controller, which usually has a comparison element and a control element, calculates in this preferred embodiment of the invention as a result of a digital control variable, using which the reference variable is performed against the desired value. The comparison element can be omitted in the present case, since the setpoint or the constant reference variable is equal to zero and the feedback variable supplied to the control element is equal to the control difference.

Das Regelglied, welches vorzugsweise als PID-Regler arbeitet, wertet die Regeldifferenz, also die Information darüber, ob, wie und wie weit die Regelgrösse bzw. die Rückführungsgrösse vom aktuellen Sollwert abweicht, als Eingangsgrösse aus und berechnet daraus eine digitale Reglerausgangsgrösse, die zur Regeldifferenz und zur erfolgten Gewichtsänderung korrespondiert und somit einer gespeicherten digitalen Stellgrösse überlagert wird, die zum Gewicht korrespondiert, welches vor der Gewichtsänderung gemessen wurde.The control element, which preferably operates as a PID controller, evaluates the control difference, ie the information as to whether, how and how far the controlled variable or the feedback variable deviates from the current setpoint, as an input variable and calculates a digital controller output variable, which is the control difference and corresponding to the weight change effected and thus superimposed on a stored digital manipulated variable corresponding to the weight measured before the weight change.

Die aktualisierte digitale Stellgrösse wird in einem nachgeschalteten D/A-Wandler in eine dazu korrespondierende analoge Stellgrösse gewandelt, für die in einer Treiberschaltung ein dazu proportionaler Kompensationsstrom erzeugt und der Spule zugeführt wird.The updated digital manipulated variable is converted in a downstream D / A converter into a corresponding analog manipulated variable, for which a proportional compensation current is generated in a driver circuit and supplied to the coil.

Durch die erzeugte magnetische Kraft wird die zu messende Kraft kompensiert und der Messhebel in die Ausgangslage zurückgeführt, in der das Licht von der Lichtquelle durch die Blende zu gleichen Teilen zu den beiden Fotodioden gelangt. In dieser Position wird die Regeldifferenz wieder Null.Due to the magnetic force generated, the force to be measured is compensated and the measuring lever is returned to the initial position, in which the light from the light source passes through the diaphragm in equal parts to the two photodiodes. In this position the control difference becomes zero again.

Bei einer Änderung des auf der Waage aufliegenden Gewichts von z.B. einem Prozent wird die Blende verschoben, wodurch eine Differenz der Fotoströme resultiert, die durch eine Änderung der digitalen Stellgrösse korrigiert wird. Liegt z.B. ein Gewicht von 1000g auf der Waagschale, so hat die Stellgrösse z.B. den binären Wert 1111101000. Bei einer Abweichung von 1 % bzw. bei der Erhöhung des Gewichts um 10g resultiert eine entsprechende Regeldifferenz und der Regler in der Ausgestaltung eines Proportionalreglers berechnet eine digitale Reglerausgangsgrösse mit dem Wert 1010. Unter Berücksichtigung der ermittelten digitalen Reglerausgangsgrösse wird der Wert der Stellgrösse somit erhöht und liegt nach der Gewichtsänderung bei 1111110010.When changing the weight on the balance of e.g. one percent, the aperture is shifted, resulting in a difference of the photocurrents, which is corrected by a change of the digital manipulated variable. If, for example, a weight of 1000 g on the weighing pan, the manipulated variable has e.g. the binary value 1111101000. With a deviation of 1% or with the increase of the weight by 10g, a corresponding control difference results and the controller in the configuration of a proportional controller calculates a digital controller output variable with the value 1010. Taking into account the determined digital controller output variable, the value becomes the manipulated variable thus increased and is after the weight change at 1111110010.

Vorzugsweise ist der Regler ein Rechner, in dem ein Betriebsprogramm implementiert ist, mittels dessen Messprozesse steuerbar sind. Die digitale Stellgrösse wird dabei vorzugsweise unter Berücksichtigung des gesteuerten Messprozesses berechnet, wobei z.B. für eine erwartete Gewichtsänderung von einem Prozent bereits vorab eine Änderung der Stelle Grösse um 0,5 % vorgenommen und der digitale Stellwert von 1111101000 auf 1111101101 gesetzt und nach Eintreten der Gewichtsänderung gegen den Endwert geführt wird.Preferably, the controller is a computer in which an operating program is implemented, by means of which measurement processes can be controlled. The digital manipulated variable is preferably calculated taking into account the controlled measuring process, wherein e.g. for an expected weight change of one percent, a change in the position size of 0.5% is made in advance and the digital control value of 1111101000 is set to 1111101101 and guided to the final value after the weight change has occurred.

Ferner können Filter gesetzt werden, mittels denen die digitalen Messgrössen gefiltert werden. Die Filterparameter können wiederum unter Berücksichtigung der erwarteten Änderungen gewählt werden, sodass Filterprozesse wenig Zeit in Anspruch nehmen oder optimierte Signalformen resultieren.Furthermore, filters can be set by means of which the digital measured variables are filtered. The filter parameters can in turn take into account the expected Changes are selected so that filtering processes take little time or optimized waveforms result.

In einer weiteren vorzugsweisen Ausgestaltung wird der Regler mit wenigstens einem Sensor verbunden, mittels dessen eine Störgrösse gemessen und die digitale Stellgrösse unter Berücksichtigung der aufgetretenen Störung berechnet wird. Der Regler wird dazu vorzugsweise mit Softwareroutinen versehen, die für die Behandlung der betreffenden Störungen vorgesehen sind.In a further preferred embodiment, the controller is connected to at least one sensor, by means of which a disturbance variable is measured and the digital manipulated variable is calculated taking into account the interference that has occurred. The controller is preferably provided with software routines that are provided for the treatment of the disorders in question.

Die erfindungsgemässe Waage mit elektromagnetischer Kraftkompensation kann somit derart an die Umgebung und an Messprozesse angepasst werden, die den Regelprozess beeinflussen, dass optimale Messresultate erzielt werden können.The inventive balance with electromagnetic force compensation can thus be adapted to the environment and to measurement processes that influence the control process that optimal measurement results can be achieved.

Nachfolgend wird die Erfindung anhand von Zeichnungen näher erläutert. Dabei zeigt:

Fig. 1
die eingangs beschriebene und aus [1], DE 101 53 603 A1 , bekannte Waage mit elektromagnetischer Kraftkompensation,
Fig. 2a
die eingangs beschriebene Differenzmessschaltung 1' der Waage von Fig. 1 mit einem Schalter SW in einer ersten Position, in der nur der Fotostrom I1 einer ersten Fotodiode D1 in der Differenzmessschaltung 1' verarbeitet wird;
Fig. 2b
die Differenzmessschaltung 1' von Fig. 2a mit dem Schalter SW in einer zweiten Position, in der nur der Fotostrom I2 einer zweiten Fotodiode D2 in der Differenzmessschaltung 1' verarbeitet wird;
Fig. 3a
die erfindungsgemässe Differenzmessschaltung 1 mit zwei Fotodioden D1, D2, von denen ein Fotostrom I1 direkt und ein Fotostrom I2 über einen Inverter INV zu einem Knotenpunkt KΔ geführt werden sowie mit einem Schalter SW, der einen Referenzstrom IRef bzw. IRef1, IRef2 innerhalb einer Periodendauer alternierend dem ersten und dem zweiten Fotostrom I1 bzw. I2 überlagert;
Fig. 3b
die Differenzmessschaltung 1 von Fig. 3a mit dem Schalter SW in einer Position, in der der Referenzstrom IRef bzw. IRef1, IRef2 dem zweiten Fotostrom I2 überlagert wird;
Fig. 4
Signalverläufe von Strömen und Signalen, die innerhalb der Differenzmessschaltung 1 von Fig. 3a bei idealen Arbeitsbedingungen auftreten; und
Fig. 5
eine erfindungsgemässe Waage mit elektromagnetischer Kraftkompensation, die eine Regeleinrichtung 10 umfasst, innerhalb der der Differenzmessschaltung 1 von Fig. 3a die Fotoströme I1 und I2 als Regelgrössen zugeführt werden und von der ein pulsweitenmoduliertes Signal sPWM einem digitalen Regler RD zugeführt wird.
The invention will be explained in more detail with reference to drawings. Showing:
Fig. 1
those described in the beginning and in [1], DE 101 53 603 A1 known balance with electromagnetic force compensation,
Fig. 2a
the difference measuring circuit 1 'of the scale of Fig. 1 with a switch SW in a first position, in which only the photocurrent I1 of a first photodiode D1 in the differential measuring circuit 1 'is processed;
Fig. 2b
the differential measuring circuit 1 'of Fig. 2a with the switch SW in a second position, in which only the photocurrent I2 of a second photodiode D2 in the differential measuring circuit 1 'is processed;
Fig. 3a
the inventive difference measuring circuit 1 with two photodiodes D1, D2, of which a photocurrent I 1 directly and a photocurrent I 2 via an inverter INV to a node K Δ are performed and with a switch SW, a reference current I Ref or I Ref1, I Ref2 alternately within a period of time superimposed on the first and the second photocurrent I 1 and I 2 ;
Fig. 3b
the differential measuring circuit 1 of Fig. 3a with the switch SW in a position in which the reference current I Ref or I Ref1, I Ref2 is superimposed on the second photocurrent I 2 ;
Fig. 4
Waveforms of currents and signals that are within the differential measuring circuit 1 of Fig. 3a in ideal working conditions occur; and
Fig. 5
an inventive balance with electromagnetic force compensation, which includes a control device 10, within the differential measuring circuit 1 of Fig. 3a the photocurrents I 1 and I 2 are supplied as controlled variables and from which a pulse width modulated signal s PWM is fed to a digital controller R D.

Die in Fig. 1 gezeigte Waage mit elektromagnetischer Kraftkompensation sowie die in den Figuren 2a und 2b gezeigte Differenzmessschaltung 1' wurden eingangs beschrieben.In the Fig. 1 shown balance with electromagnetic force compensation and in the FIGS. 2a and 2 B shown differential measuring circuit 1 'have been described above.

Fig. 3a zeigt eine erfindungsgemässe Differenzmessschaltung 1, die bei der Waage mit elektromagnetischer Kraftkompensation von Fig. 5 in einer Regeleinrichtung 10 eingesetzt wird. Fig. 3a shows a differential measuring circuit 1 according to the invention, which in the balance with electromagnetic force compensation of Fig. 5 is used in a control device 10.

Die Differenzmessschaltung 1 von Fig. 3a umfasst zwei Fotodioden D1, D2, denen Licht von einer Lichtquelle D3, vorzugsweise einer Leuchtdiode, durch eine Öffnung 106a in einer verschiebbaren Blende zuführbar ist, die an einem zweiten Endstück 106b eines drehbar gelagerten Messhebels 106 vorgesehen ist, wie dies bereits mit Bezug auf Fig. 1 beschrieben wurde. In der Ausgangslage der Blende wird Licht gleichmässig auf beide Fotodioden D1 und D2 übertragen, sodass diese gleich grosse Fotoströme I1 und I2 an Anschlussleitungen I1, I2 abgeben. Bei einer Änderung der Krafteinwirkung auf den Messhebel 106 und einer Verschiebung der Blende werden die Fotodioden D1 und D2 mit unterschiedlichen Lichtanteilen beaufschlagt, weshalb unterschiedliche Fotoströme I1 und I2 an die Anschlussleitungen I1, I2 abgegeben werden.The differential measuring circuit 1 of Fig. 3a comprises two photodiodes D1, D2, to which light from a light source D3, preferably a light emitting diode, can be fed through an aperture 106a in a slidable aperture provided on a second end 106b of a rotatably mounted measuring lever 106, as already described with reference to FIG Fig. 1 has been described. In the initial position of the diaphragm, light is uniformly transmitted to both photodiodes D1 and D2, so that they deliver the same large photocurrents I 1 and I 2 to connection lines I1, I2. When changing the force on the measuring lever 106 and a shift of the diaphragm, the photodiodes D1 and D2 are exposed to different light components, which is why different photocurrents I 1 and I 2 are delivered to the connecting lines I1, I2.

Die Kathoden der Fotodioden D1 und D2 sind permanent mit einem gemeinsamen Spannungspotential UB und nicht wie bei der Schaltungsanordnung von Fig. 2a mit einem Schalter verbunden. Die Fotodioden D1 und D2 können daher in einem gewählten Arbeitsbereich stabil betrieben werden. Vorzugsweise wird an die Kathoden der Fotodioden D1 und D2 ein positives Spannungspotential UB bzw. eine positive Vorspannung oder Sperrspannung angelegt, wodurch die Fotodioden D1 und D2 Sperrbereich betrieben werden. Von der Anode der ersten Fotodiode D1 wird ein erster Fotostrom I1 einem Knotenpunkt KΔ direkt zugeführt. Von der Anode der zweiten Fotodiode D2 wird ein zweiter Fotostrom I2 über einen Inverter INV dem Knotenpunkt KΔ direkt zugeführt. Im Inverter INV wird die Polarität des zweiten Fotostroms I2 invertiert, dem gegebenenfalls ein Referenzstrom IRef2 überlagert ist.The cathodes of the photodiodes D1 and D2 are permanently connected to a common voltage potential UB and not as in the circuit arrangement of Fig. 2a connected to a switch. The photodiodes D1 and D2 can therefore be operated stably in a selected operating range. Preferably, a positive voltage potential U B or a positive bias voltage or reverse voltage is applied to the cathodes of the photodiodes D1 and D2, whereby the photodiodes D1 and D2 stop band are operated. From the anode of the first photodiode D1, a first photocurrent I 1 is fed directly to a node K Δ . From the anode of the second photodiode D2, a second photocurrent I 2 via an inverter INV the node K Δ fed directly. In the inverter INV, the polarity of the second photocurrent I 2 is inverted, to which optionally a reference current I Ref2 is superimposed.

Dazu wird der zweite Fotostrom I2 dem invertierenden Eingang eines ersten Operationsverstärkers OAINV zugeführt, dessen Ausgang einerseits über einen ersten Widerstand R1 mit dem invertierenden Eingang und andererseits über einen zweiten Widerstand R2 mit dem Knotenpunkt KΔ verbunden ist. Der zweite Fotostrom I2 durchfliesst den ersten Widerstand R1, weshalb über dem ersten Widerstand R1 eine Spannung resultiert, die dem Produkt I2 * R1 entspricht. Da sowohl der erste und der zweite Widerstand R1, R2 mit einem Ende virtuell an Masse liegen, resultiert über dem zweiten Widerstand R2 dasselbe Spannungspotential wie über dem ersten Widerstand R1. Da beide Widerstände R1, R2 gleich gross sind aber mit unterschiedlichen Enden an Masse liegen, fliesst im Widerstand R2 derselbe Strom wie im Widerstand R1, aber mit umgekehrtem Vorzeichen. Der zweite Fotostrom I2 wird dem Knotenpunkt KΔ daher mit umgekehrter Polarität zugeführt.For this purpose, the second photocurrent I 2 is supplied to the inverting input of a first operational amplifier OA INV whose output is connected on the one hand via a first resistor R1 to the inverting input and on the other hand via a second resistor R2 to the node K Δ . The second photocurrent I 2 flows through the first resistor R1, which is why over the first resistor R1 results in a voltage corresponding to the product I 2 * R1. Since both the first and second resistors R1, R2 are virtually grounded at one end, the same voltage potential results across the second resistor R2 as across the first resistor R1. Since both resistors R1, R2 are the same size but with different ends to ground, flows in the resistor R2, the same current as in the resistor R1, but with the opposite sign. The second photocurrent I 2 is therefore supplied to the node K Δ in reverse polarity.

Durch den Schalter SW, der innerhalb einer Periodendauer einmal vor und wieder zurück geschaltet wird, wird in einem ersten Periodenanteil t1 in der Position zt1 ein Referenzstrom IRef1 dem ersten Fotostrom I1 überlagert. In einem zweiten Periodenanteil t2 in der Position zt2 wird der Referenzstrom IRef2 dem zweiten Fotostrom I2 überlagert.By the switch SW, which is switched back and forth again within a period duration, a reference current I Ref1 is superimposed on the first photocurrent I 1 in a first period component t 1 in the position z t1 . In a second period proportion t 2 in the position zt 2 , the reference current I Ref2 is superimposed on the second photocurrent I 2 .

Der symbolisch gezeigte Umschaltkontakt des Schalters SW, der vorzugsweise als Halbleiterschalter ausgebildet ist, ist über einen Referenzwiderstand RRef mit eigener Referenzspannung URef verbunden. Der Referenzstrom IRef entspricht daher dem Quotienten URef/RRef. Beide Punkte, an denen der Referenzströme IRef1 bzw. IRef2 dem betreffenden Fotostrom I1 bzw. I2 überlagert werden, liegen virtuell an Masse, weshalb in beiden Position des Schalters SW die Referenzspannung URef am Referenzwiderstand RRef anliegt und die beiden Referenzströme IRef1 bzw. IRef2 identisch sind und vereinfachend auf einen einzigen Referenzstrom IRef Bezug genommen werden kann.The symbolically shown switching contact of the switch SW, which is preferably designed as a semiconductor switch, is connected via a reference resistor R Ref with its own reference voltage U Ref . The reference current I Ref therefore corresponds to the quotient U Ref / R Ref . Both points at which the reference currents I Ref1 and I Ref2 are superimposed on the respective photocurrent I 1 and I 2 are virtually grounded, which is why in both positions of the switch SW the reference voltage U Ref is applied to the reference resistor R Ref and the two reference currents I Ref1 or I Ref2 are identical and can be simplified reference to a single reference current I Ref .

Da auf eine Umschaltung der Fotoströme I1 und I2 verzichtet und stattdessen der Referenzstrom IRef umgeschaltet wird, ergeben sich stabilere Verhältnisse, die es vorteilhaft erlauben anstelle einer Referenzspannungsquelle eine Betriebsspannung der Schaltungsanordnung als Referenzspannung URef zu verwenden.Since there is no switching over of the photocurrents I 1 and I 2 and instead the reference current I Ref is switched over, more stable conditions result that advantageously allow an operating voltage of the circuit arrangement to be used as the reference voltage U Ref instead of a reference voltage source.

Der Knotenpunkt KΔ liegt am Eingang eines Integrators INT bzw. am invertierenden Eingang eines darin vorgesehenen zweiten Operationsverstärkers OAINT, dessen Ausgang über einen Kondensator CINT mit dem Knotenpunkt KΔ verbunden ist, weshalb die in den Periodenanteilen t1, t2 auftretenden Differenzströme als Integratorstrom IINT dem Kondensator CINT zufliessen und diesen laden oder entladen. Sofern sich die Ströme am Knotenpunkt KΔ gegenseitig aufheben, bleiben die Ladung des Kondensators CINT und dessen Ausgangssignal bzw. das Integratorsignal sINT am Ausgang des zweiten Operationsverstärkers OAINT unverändert. Durch die alternierende Zuschaltung des Referenzstroms IRef in den beiden Periodenanteilen t1, t2 soll dieser Zustand erreicht werden, sobald das Integratorsignal SINT, zum Zeitpunkt, an dem sich das Integratorsignal sINT und das Rampensignal sRAMP schneiden, proportional zur Auslenkung der Blende und zur Differenz der Fotoströme I1, I2 ist. Somit ist das Integratorsignal sINT zu messen und mit einem Referenzsignal zu vergleichen und in Abhängigkeit davon ein entsprechendes Umschaltsignal für den Schalter SW derart zu erzeugen, dass der Differenzstrom am Knotenpunkt KΔ gleich Null wird, wenn das Integratorsignal sINT einen Wert erreicht hat, der proportional zur Auslenkung der Blende ist.The node K Δ is located at the input of an integrator INT or at the inverting input of a second operational amplifier OA INT provided therein, whose Output is connected via a capacitor C INT to the node K Δ, which is why the difference currents occurring in the period components t 1 , t 2 inflow as integrator current I INT to the capacitor C INT and load or discharge this. If the currents cancel each other at the node K Δ , the charge of the capacitor C INT and its output signal or the integrator signal s INT at the output of the second operational amplifier OA INT remain unchanged. Due to the alternating connection of the reference current I Ref in the two period components t 1 , t 2 , this state is to be achieved as soon as the integrator signal SINT , at the time at which the integrator signal s INT and the ramp signal s RAMP intersect, is proportional to the deflection of the diaphragm and to the difference of the photocurrents I 1 , I 2 . Thus, the integrator signal s INT is to be measured and compared with a reference signal and to generate a corresponding switching signal for the switch SW such that the differential current at the node K Δ becomes zero when the integrator signal s INT has reached a value, which is proportional to the deflection of the diaphragm.

Dazu wird das Integratorsignal sINT einem Komparator CMP bzw. darin dem nicht invertierenden Eingang eines dritten Operationsverstärkers OACMP zugeführt, an dessen invertierenden Eingang ein Rampensignal sRAMP angelegt wird, das vorzugsweise zum Spannungsbereich korrespondiert, der vom Integratorsignal sINT durchlaufen werden kann. Das Rampensignal sRAMP wird von einem Rampengenerator RG erzeugt an dessen Eingang ein Zählersignal eines ersten Zählers angelegt wird. Der erste Zähler Z1 zählt periodisch hoch, wobei der Rampengenerator RG ein entsprechendes analoges Signal erzeugt. Nach Ablauf der Periodendauer wird der erste Zähler Z1 zurückgesetzt und läuft erneut hoch. Sobald das Rampensignal sRAMP den Wert des Integratorsignals sINT erreicht, schaltet der Komparator bzw. der erste Operationsverstärker OACMP um, weshalb an dessen Ausgang ein pulsweitenmoduliertes Komparatorsignal sPWM resultiert.For this purpose the integrator signal s INT is supplied to a comparator CMP or in the non-inverting input of a third operational amplifier OA CMP, a ramp signal s RAMP is applied to the inverting input of which preferably corresponds to the voltage range which can be traversed by the integrator signal s INT. The ramp signal s RAMP is generated by a ramp generator RG at whose input a counter signal of a first counter is applied. The first counter Z1 counts up periodically, wherein the ramp generator RG generates a corresponding analog signal. After the period has expired, the first counter Z1 is reset and starts up again. As soon as the ramp signal s RAMP reaches the value of the integrator signal s INT , the comparator or the first operational amplifier OA CMP switches over, for which reason a pulse-width-modulated comparator signal s PWM results at its output.

Das Komparatorsignal sPWM wird in der Folge dem Steuereingang des Schalters SW zugeführt, sodass die Zeitperioden t1, t2, in denen der Referenzstrom IRef den Fotoströmen I1, I2 überlagert wird so lange geändert werden, bis am Knotenpunkt KΔ im Mittel eine Stromdifferenz von Null auftritt und die dem Kondensator CINT zugeführten und entnommenen Ladungen sich kompensieren.The comparator signal s PWM is subsequently supplied to the control input of the switch SW, so that the time periods t 1 , t 2 in which the reference current I Ref is superimposed on the photocurrents I 1 , I 2 are changed until at the node K Δ im Means a current difference of zero occurs and compensate for the capacitor C INT supplied and removed charges.

Das Komparatorsignal sPWM wird zudem für die Regelung der Blende verwendet, wobei in einem zweiten Zähler Z2 aus dem Komparatorsignal sPWM eine digitale Mess- oder Rückführungsgrösse sMG abgeleitet wird, wie dies oben beschrieben wurde. Der zweite Zähler Z2 zählt z.B. die Anzahl Schritte nach Auftreten des Polaritätswechsels bis zum Erreichen des Sollwerts der Blende oder, sofern eine Auslenkung der Blende in die andere Richtung erfolgt ist, vom Sollwert bis zum Auftreten des Polaritätswechsels.The comparator signal s PWM is also used to control the aperture, wherein in a second counter Z2 from the comparator signal s PWM a digital measurement or feedback variable s MG is derived, as described above. The second Counter Z2 counts, for example, the number of steps after occurrence of the polarity change until reaching the desired value of the diaphragm or, if a deflection of the diaphragm in the other direction has taken place, from the setpoint to the occurrence of the polarity change.

Der erste und der zweite Zähler Z1, Z2 sind vorzugsweise in einem gemeinsamen Zählermodul Z enthalten. Beispielsweise wird der nachstehend genannte Regler RD mittels eines Prozessors realisiert, der mehrere Zähler umfasst, die wahlweise programmierbar sind.The first and second counters Z1, Z2 are preferably contained in a common counter module Z. For example, the controller R D mentioned below is realized by means of a processor comprising a plurality of counters which are optionally programmable.

Die ermittelte digitale Mess- oder Rückführungsgrösse sMG wird vom Ausgang der Differenzmessschaltung 1 zum Eingang eines digitalen Reglers RD geführt. Da die Führungsgrösse dFG vorzugsweise gleich Null ist und die Mess- oder Rückführungsgrösse sMG somit die Regelabweichung bildet und gegen Null zu regeln ist, wird diese von einem Regelglied zugeführt, das eine dazu korrespondierende digitale Stellgrösse dSG berechnet, mittels der die Blende wieder in die Ausgangslage zurückgeführt wird. Wie dies oben erläutert wurde, wird für eine Gewichtsänderung jeweils die notwendige Änderung der Stellgrösse dSG berechnet, mit der die Blende zuvor für ein bestimmtes Gewicht in die Ausgangslage geführt wurde. Die vom Regler RD ermittelte Stellgrösse wird somit zu einer gespeicherten Stellgrösse addiert, die zum Gericht korrespondiert, die vor der Gewichtsänderung gemessen wurde.The determined digital measuring or feedback variable s MG is fed from the output of the differential measuring circuit 1 to the input of a digital controller R D. Since the reference variable d FG is preferably equal to zero and the measuring or feedback variable s MG thus forms the control deviation and is to be regulated to zero, this is supplied by a control element which calculates a corresponding digital manipulated variable d SG , by means of the aperture again is returned to the starting position. As has been explained above, the necessary change in the manipulated variable d SG is calculated in each case for a weight change, with which the diaphragm was previously guided to the starting position for a specific weight. The control variable determined by the controller R D is thus added to a stored control variable corresponding to the court, which was measured before the weight change.

Fig. 3b zeigt die Differenzmessschaltung 1 von Fig. 3a mit dem Schalter SW in einer Position, in der der Referenzstrom IRef2 bzw. IRef dem zweiten Fotostrom I2 überlagert wird. Nun wird die Summe des zweiten Fotostroms I2 und des Referenzstroms IRef dem Inverter INV zugeführt und von diesem am Ausgang invertiert abgegeben. Fig. 3b shows the differential measuring circuit 1 of Fig. 3a with the switch SW in a position in which the reference current I Ref2 or I Ref is superimposed on the second photocurrent I 2 . Now, the sum of the second photocurrent I 2 and the reference current I Ref is supplied to the inverter INV and output from this at the output inverted.

Fig. 4 zeigt Signalverläufe von Strömen und Signalen, die innerhalb der Differenzmessschaltung 1 von Fig. 3a auftreten. Zuerst sind die Verläufe der Referenzströme IRef1, IRef2 gezeigt, die durch alternierende Betätigung des Schalters SW dem ersten und dem zweiten Fotostrom I1, I2 überlagert werden. Das dritte Diagramm zeigt den Verlauf des Integratorstroms IINT. Das vierte Diagramm zeigt das Integratorsignal sINT und das periodisch und sägezahnförmig verlaufende Rampensignal sRAMP. Im letzten Diagramm ist das rechteckförmige und pulsweitenmodulierte Komparatorsignal sCMP gezeigt, welches ansteigende Flanken beim Abfallen des Rampensignals sRAMP und abfallende Flanken zu den Zeitpunkten aufweist, zu denen das Rampensignal sRAMP den Wert Integratorsignals sINT durchläuft. Fig. 4 shows waveforms of currents and signals that are within the differential measuring circuit 1 of Fig. 3a occur. First, the curves of the reference currents I Ref1, I Ref2 are shown, which are superimposed on the first and the second photocurrent I 1 , I 2 by alternating actuation of the switch SW. The third diagram shows the course of the integrator current I INT . The fourth diagram shows the integrator signal s INT and the periodic and sawtooth ramp signal s RAMP . The last diagram shows the rectangular and pulse-width-modulated comparator signal s CMP , which has rising edges when the ramp signal s RAMP drops and falling edges at the times at which the ramp signal s RAMP passes through the value integrator signal s INT .

Es ist ersichtlich, dass eine aufgetretene Regelabweichung ausgeregelt wird und dass pulsweitenmodulierte Komparatorsignal sCMP sowie die davon abhängigen beiden ersten Signalverläufe IRef1, IRef2 hin zu einem Tastverhältnis von 50/50 geregelt werden. Konsequenterweise ändert sich auch der Integratorstrom IINT entsprechend. Das Integratorsignal sINT läuft hoch und liegt zuletzt etwa in der Mitte des Verlaufs des Rampensignals sRAMP, wodurch am Ausgang des Komparators CMP das pulsweitenmodulierte Komparatorsignal sCMP mit einem Tastverhältnis von 50/50 resultiert.It can be seen that a control deviation which has occurred has been corrected and that the pulse width modulated comparator signal s CMP and the two dependent thereon first signal waveforms I Ref1, I Ref2 are regulated to a duty cycle of 50/50. Consequently, the integrator current I INT changes accordingly. The integrator signal s INT runs high and lies last approximately in the middle of the course of the ramp signal s RAMP , resulting in the output of the comparator CMP, the pulse width modulated comparator signal s CMP with a duty cycle of 50/50 results.

Fig. 5 zeigt eine erfindungsgemässe Waage mit elektro-magnetischer Kraftkompensation, die eine Regeleinrichtung 10 umfasst, innerhalb der der Differenzmessschaltung 1 von Fig. 3a die Fotoströme I1 und I2 als Regelgrössen zugeführt werden und von der ein pulsweitenmoduliertes Signal sPWM einem digitalen Regler RD zugeführt wird, der die oben beschriebenen Aufgaben erfüllt. Fig. 5 shows a scale according to the invention with electro-magnetic force compensation, which includes a control device 10, within the differential measuring circuit 1 of Fig. 3a the photocurrents I 1 and I 2 are supplied as controlled variables and from which a pulse-width-modulated signal s PWM is fed to a digital controller R D , which fulfills the tasks described above.

Da in dieser Ausgestaltung der Schaltungsanordnung das vorzugsweise pulsweitenmodulierte Signal sPWM und nicht die Regelabweichung zum Regler RD übertragen wird, ermittelt der erweiterte prozessorgesteuerte Regler RD, z.B. in der oben beschriebenen Weise, die Regelabweichung und ermittelt eine digitale Stellgrösse dSG, die zu einem D/A-Wandler 9 übertragen wird, von dem eine dazu korrespondierende analoge Stellgrösse aSG zu einer Treiberschaltung 2 überträgt, die einen Kompensationsstrom Icomp an die Kompensationsspule 110 abgibt.Since in this embodiment of the circuit arrangement the preferably pulse-width modulated signal PWM and not the control deviation is transmitted to the controller R D , the extended processor-controlled controller R D , for example in the manner described above, determines the control deviation and determines a digital manipulated variable d SG , the is transmitted to a D / A converter 9, from which a corresponding analog manipulated variable a SG transmits to a driver circuit 2, which outputs a compensation current I com p to the compensation coil 110.

In vorzugsweisen Ausgestaltungen werden bei der Verarbeitung der Signale im Regelkreis von Fig. 5 erfindungsgemäss Informationen berücksichtigt, die den Messprozess beeinflussen können und nicht unmittelbar von einer Verschiebung der Blende bzw. einer Drehung des Messhebels 106 abgeleitet werden, sondern von weiteren Informationsquellen geliefert werden.In preferred embodiments, in the processing of the signals in the control loop of Fig. 5 According to the invention, information is taken into account which can influence the measuring process and is not derived directly from a displacement of the diaphragm or a rotation of the measuring lever 106, but is supplied by further information sources.

Mittels Sensoren 4 werden auf die Waage einwirkende Störungen x erfasst und entsprechende Messsignale mx an den Regler RD geliefert. Zur Behandlung dieser Störungen sind Softwareroutinen 7 mit Instruktionen zur entsprechenden Einflussnahme auf den Regelkreis vorgesehen.By means of sensors 4 disturbances x acting on the balance are detected and corresponding measurement signals mx are supplied to the controller RD. To handle these disturbances, software routines 7 are provided with instructions for influencing the control loop accordingly.

Auch durch Bewegungen des Messguts können Störungen x auf den Regelungsprozess einwirken. Diese Bewegungen des Messguts können wiederum mittels Sensoren 4 erfasst oder durch Betriebsprogramme in der Waage oder in einem Leitrechner L gemeldet werden.Disturbances x can also influence the control process through movements of the material being measured. These movements of the material to be measured can in turn be detected by means of sensors 4 or reported by operating programs in the balance or in a control computer L.

Die einzelnen Reglerparameter werden vorzugsweise in Abhängigkeit der genannten Einwirkungen bzw. Störungen entsprechend gesteuert. Bei der Verwendung eines PID Reglers werden beim Auftreten von Störungen die Gewichtungsfaktoren, der P-, I- und D-Komponenten entsprechend gewichtet. Zudem kann vorausschauend eine Regelabweichung eingeführt werden, mittels der eine erwartete Gewichtsänderung kompensiert wird.The individual controller parameters are preferably controlled accordingly as a function of the aforementioned actions or disturbances. When using a PID Controllers are weighted according to the weighting factors, the P, I and D components when disturbances occur. In addition, a control deviation can be introduced with foresight by means of which an expected weight change is compensated.

Ferner können digitale Filter 5 eingesetzt oder deren Filterparameter geändert werden, um die im digitalen Regler RD verarbeitet Signale zu filtern.Furthermore, digital filters 5 can be used or their filter parameters can be changed in order to filter the signals processed in the digital controller R D.

Literaturverzeichnisbibliography

  1. [1] DE101 53 603 A1 [1] DE101 53 603 A1
  2. [2] US 3,727,708 A [2] US 3,727,708 A
  3. [3] DE 2 311 676 A [3] DE 2 311 676 A
Liste der BezugszeichenList of reference numbers

11
Erfindungsgemässe DifferenzmessschaltungDifference measuring circuit according to the invention
1'1'
Differenzmessschaltung gemäss Stand der TechnikDifferential measuring circuit according to the prior art
22
Treiberschaltungdriver circuit
44
Sensorsensor
55
digitaler Filterdigital filter
7, cx7, cx
Softwareroutinensoftware routines
8, OS8, OS
Betriebsprogrammoperating program
99
D/A-WandlerD / A converter
1010
erfindungsgemässe RegeleinrichtungControl device according to the invention
10'10 '
Regeleinrichtung gemäss Stand der TechnikControl device according to the prior art
101101
Gehängehanger
101 a101 a
Auslegerboom
103103
ParallelführungslenkerParallel guide link
103a103a
Biegelagerflexure pivot
104104
Konsoleconsole
104a104a
Winkelteilangle part
104b104b
Teil der KonsolePart of the console
105105
Koppelpaddock
106106
beweglicher Messhebelmovable measuring lever
106a106a
Schlitzöffnungslot opening
106b106b
zweites Endstück, Blendesecond tail, aperture
106c106c
erstes Endstückfirst tail
107107
Biegelagerflexure pivot
109109
PermanentmagnetsystemPermanent magnet system
110110
SpuleKitchen sink
111111
opto-elektrische MessvorrichtungOpto-electrical measuring device
D1D1
erste Fotodiodefirst photodiode
D2D2
zweite Fotodiodesecond photodiode
D3D3
Lichtquellelight source
I0 I 0
Referenzstromreference current
I1I1
erster Fotostromfirst photocurrent
I2I2
zweiter Fotostromsecond photocurrent
Icomp I comp
Kompensationsstromcompensating current
IRef1 I Ref1
erster Referenzstromfirst reference current
IRef2 I Ref2
zweiter Referenzstromsecond reference current
IINT I INT
Integratorstromintegrator current
U∑ U Σ
Summenspannungsum voltage
UΔ U Δ
Differenzspannung, proportionales AusgangssignalDifferential voltage, proportional output signal
U0 U 0
ReferenzspannungsquelleReference voltage source
URef U ref
Referenzspannungreference voltage
UB U B
Spannungspotentialvoltage potential
R0 R 0
Referenzwiderstandreference resistor
R1R1
erster Widerstandfirst resistance
R2R2
zweiter Widerstandsecond resistance
RΔ R Δ
Widerstand des ersten OperationsverstärkersResistance of the first operational amplifier
RRef R Ref
Referenzwiderstandreference resistor
C∑ C Σ
Kondensator des zweiten OperationsverstärkersCapacitor of the second operational amplifier
CΔ C Δ
Kondensator des ersten OperationsverstärkersCapacitor of the first operational amplifier
CINT C INT
Kondensator des IntegratorsCapacitor of the integrator
K∑ K Σ
Knotenpunkt des zweiten OperationsverstärkersNode of the second operational amplifier
KΔ K Δ
Knotenpunkt des ersten OperationsverstärkersNode of the first operational amplifier
zt1 z t1
Schalterzustand im ersten PeriodenanteilSwitch state in the first period share
zt2 z t2
Schalterzustand im zweiten PeriodenanteilSwitch state in the second period proportion
t1t1
erster Periodenanteilfirst period share
t2t2
zweiter Periodenanteilsecond period share
sINT s INT
Integratorsignalintegrator signal
sRAMP s RAMP
Rampensignalramp signal
sPWM s PWM
pulsweitenmoduliertes Komparatorsignalpulse width modulated comparator signal
sCMP s CMP
Komparatorsignalcomparator
sMG s MG
Mess- oder RückführungsgrösseMeasuring or feedback variable
dMG d MG
Digitale MessgrösseDigital measurand
dSG SG
digitale Stellgrössedigital manipulated variable
dFG d FG
digitale Führungsgrössedigital reference variable
aSG a SG
analoge Stellgrösseanalog manipulated variable
xx
Störungdisorder
mxmx
Messsignalmeasuring signal
A/DA / D
Wandlermodulconverter module
DSPDSP
Anzeigeeinheitdisplay unit
CTRLCTRL
Steuereinheitcontrol unit
SWSW
Schalterswitch
OA∑ OA Σ
zweiter Operationsverstärkersecond operational amplifier
OAΔ OA Δ
erster Operationsverstärkerfirst operational amplifier
OAINV OA INV
invertierender Eingang des ersten Operationsverstärkersinverting input of the first operational amplifier
OAINT OA INT
zweiten Operationsverstärkersecond operational amplifier
OACMP OA CMP
dritter Operationsverstärkerthird operational amplifier
INVINV
Inverterinverter
INTINT
Integratorintegrator
ZZ
Zählermodulcounter module
Z1Z1
erster Zählerfirst counter
Z2Z2
zweiter Zählersecond counter
CMPCMP
Komparatorcomparator
RGRG
Rampengeneratorramp generator
RD R D
digitaler Reglerdigital controller
LL
Leitrechnermaster computer

Claims (15)

Differenzmessschaltung (1) für eine Waage mit elektromagnetischer Kraftkompensation, der von zwei Fotodioden (D1, D2) abgegebene Fotoströme (I1, I2) zuführbar sind und die geeignet ist, ein zur Differenz dieser Fotoströme (I1, I2) proportionales Ausgangssignal zu erzeugen, mit einem Schalter (SW), der innerhalb von zwei Periodenanteilen t, t2 einer Periodendauer T zwischen zwei Zuständen (zt1, zt2) umschaltbar ist, um den Stromfluss durch einen Knotenpunkt (KΔ) zu beeinflussen, dem die beiden Fotoströme (I1, I2) zuführbar sind, dadurch gekennzeichnet, dass
der Schalter (SW) derart steuerbar ist, dass ein von einer Spannungs- oder Stromquelle (URef) abgegebener Referenzstrom (IRef) innerhalb der Periodenanteile t1, t2 alternierend einem der beiden Fotoströme (I1, I2) überlagerbar ist, die dem Knotenpunkt (KΔ) permanent zufliessen;
und dass der Knotenpunkt (KΔ) am Eingang eines Integrators (INT) liegt, dessen Integratorsignal (sINT) in einem Komparator (CMP) mit einem zyklisch verlaufenden Rampensignal (sRAMP) vergleichbar ist, welches die Periodendauer T aufweist, wobei am Ausgang des Komparators (CMP) ein rechteckförmiges Komparatorsignal (sPWM) erzeugbar ist, dessen Tastverhältnis durch den Schnittpunkt des Integratorsignal (sINT) und des Rampensignals (sRAMP) definiert ist und das einem Steuereingang des Schalters (SW) zuführbar ist.Difference measuring circuit (1) for a balance with electromagnetic force compensation, the photocurrents of two photodiodes (D1, D2) supplied (I 1 , I 2 ) can be fed and which is suitable for the difference of these photocurrents (I 1 , I 2 ) proportional output signal with a switch (SW) which can be switched within two period proportions t, t 2 of a period T between two states (z t1 , z t2 ) in order to influence the current flow through a node (K Δ ) to which the two photocurrents (I 1 , I 2 ) can be fed, characterized in that
the switch (SW) is controllable such that one of a voltage or current source (U Ref) given for reference current (I Ref) within the period components t 1, t 2 alternately one of the two photo-currents (I 1, I 2) can be superimposed, which permanently flow to the node (K Δ );
and that the node (K Δ ) is located at the input of an integrator (INT) whose integrator signal (s INT ) in a comparator (CMP) is comparable to a cyclic ramp signal (s RAMP ) having the period T, wherein the output a rectangular comparator signal (s PWM ) can be generated by the comparator (CMP) whose duty cycle is defined by the intersection of the integrator signal (s INT ) and the ramp signal (s RAMP ) and which can be fed to a control input of the switch (SW). Differenzmessschaltung (1) nach Anspruch 1, dadurch gekennzeichnet, dass
die erste Elektrode der ersten Fotodiode (D1) direkt mit dem Knotenpunkt (KΔ) verbunden ist, dass die erste Elektrode der zweiten Fotodiode (D2) über einen Inverter (INV), in dem der zweite Fotostrom (I2) invertiert wird, mit dem Knotenpunkt (KΔ) verbunden ist, und dass die zweiten Elektroden der beiden Fotodioden (D1, D2) mit einem gemeinsamen Spannungspotenzial (UB) verbunden sind.Differential measuring circuit (1) according to claim 1, characterized in that
the first electrode of the first photodiode (D1) is connected directly to the node (K Δ ), that the first electrode of the second photodiode (D2) via an inverter (INV), in which the second photocurrent (I 2 ) is inverted, with the node (K Δ ) is connected, and that the second electrodes of the two photodiodes (D1, D2) are connected to a common voltage potential (U B ). Differenzmessschaltung (1) nach Anspruch 2, dadurch gekennzeichnet, dass
die erste Elektrode der zweiten Fotodiode (D2) im Inverter (INV) mit einem invertierenden Eingang eines ersten Operationsverstärkers (OAINV) verbunden ist, dessen Ausgang über einen ersten Widerstand (R1) mit dem invertierenden Eingang und über einen gleich grossen zweiten Widerstand (R2) mit dem Knotenpunkt (KΔ) verbunden ist.Differential measuring circuit (1) according to claim 2, characterized in that
the first electrode of the second photodiode (D2) in the inverter (INV) is connected to an inverting input of a first operational amplifier (OA INV ) whose output is connected via a first resistor (R1) to the inverting input and via a second resistor (R2 ) is connected to the node (K Δ ). Differenzmessschaltung (1) nach Anspruch 2 oder 3, dadurch gekennzeichnet, dass
die Spannungs- oder Stromquelle (URef) eine Betriebsspannung der Differenzmessschaltung (1) ist, die auch für andere Bauteile genutzt wird.Differential measuring circuit (1) according to claim 2 or 3, characterized in that
the voltage or current source (U Ref ) is an operating voltage of the differential measuring circuit (1), which is also used for other components. Differenzmessschaltung (1) nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass eine Lichtquelle, vorzugsweise eine Leuchtdiode (D3) vorgesehen ist, deren Strahlung durch eine verschiebbare Blende den Fotodioden (D1, D2) zuführbar ist.Difference measuring circuit (1) according to one of claims 1 to 4, characterized in that a light source, preferably a light emitting diode (D3) is provided, whose radiation is supplied to the photodiodes (D1, D2) by a displaceable aperture. Differenzmessschaltung (1) nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass der Knotenpunkt (KΔ) mit dem invertierenden Eingang eines als Integrator beschalteten zweiten Operationsverstärkers (OAINT) verbunden ist, an dessen Ausgang, der durch einen Kondensator (CINT) mit dem invertierenden Eingang verbunden ist, das Integratorsignal (sINT) anliegt.Difference measuring circuit (1) according to one of Claims 1 to 5, characterized in that the node (K Δ ) is connected to the inverting input of a second operational amplifier (OA INT ) connected as an integrator, to the output of which a capacitor (C INT ) is connected to the inverting input, the integrator signal (s INT ) is applied. Differenzmessschaltung (1) nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass das Integratorsignal (sINT) an einem ersten Eingang eines als Komparator beschalteten dritten Operationsverstärkers (OACMP) anliegt, an dessen zweitem Eingang das Rampensignal (sRAMP) anliegt, und an dessen Ausgang das Komparatorsignal (sPWM) anliegt.Differential measuring circuit (1) according to one of Claims 1 to 6, characterized in that the integrator signal (s INT ) is applied to a first input of a third operational amplifier (OA CMP ) connected as comparator, to the second input of which the ramp signal (s RAMP ) is applied, and at whose output the comparator signal (s PWM ) is applied. Differenzmessschaltung (1) nach Anspruch 7, dadurch gekennzeichnet, dass
das Rampensignal (sRAMP) in einem ersten Zähler (Z, Z1) erzeugt wird, der innerhalb der Periodendauer T von einem Anfangswert bis zu einem Endwert hochzählt und dann zurückgesetzt wird.Differential measuring circuit (1) according to claim 7, characterized in that
the ramp signal (s RAMP ) is generated in a first counter (Z, Z1) which counts up from an initial value to a final value within the period T and is then reset. Differenzmessschaltung (1) nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, dass, vorzugsweise mittels eines zweiten Zählers (Z2), aus der Differenz der Periodenanteile t1, t2 oder einem Teil davon oder aus dem Tastverhältnis des Komparatorsignals (sPWM) eine digitale Messgrösse (dMG) gebildet wird, die zumindest annähernd proportional zur Position der verschiebbaren Blende ist.Differential measuring circuit (1) according to one of claims 1 to 8, characterized in that , preferably by means of a second counter (Z2), from the difference of the period components t 1 , t 2 or a part thereof or from the duty cycle of the comparator signal (s PWM ) a digital measured variable (d MG ) is formed which is at least approximately proportional to the position of the displaceable diaphragm. Differenzmessschaltung (1) nach Anspruch 9, dadurch gekennzeichnet, dass
ein Regler (RD) vorgesehen ist, dem die digitale Messgrösse (dMG) als Regelabweichung zuführbar ist und von dem eine dazu korrespondierende digitale Stellgrösse (dSG) erzeugbar ist, mittels der die Blende gegen einen Ausgangspunkt zwischen den beiden Fotodioden (D1, D2) zurückführbar ist.Differential measuring circuit (1) according to claim 9, characterized in that
a controller (R D ) is provided to which the digital measured quantity (d MG ) can be supplied as a control deviation and from which a corresponding digital manipulated variable (d SG ) can be generated, by means of which the diaphragm is directed against a starting point between the two photodiodes (D1, D2) is traceable. Differenzmessschaltung (1) nach Anspruch 10, dadurch gekennzeichnet, dass
die vom Regler (RD) abgegebene digitale Stellgrösse (dSG) einem D/A-Wandler (9) zuführbar ist, der eine dazu korrespondierende analoge Stellgrösse (aSG) einer Treiberschaltung (2) zuführt, die einen dazu proportionalen Kompensationsstrom (Icomp) an eine Spule (110) abgibt, die von einem drehbar gelagerten Messhebel (106) in einem Magnetfeld verschiebbar gehalten ist, an dessen erstem Endstück (106c) die zu messenden Kraft einleitbar ist und an dessen zweitem Endstück (106b) die Blende vorgesehen ist.Differential measuring circuit (1) according to claim 10, characterized in that
the digital control variable (d SG ) delivered by the controller (R D ) can be supplied to a D / A converter (9) which supplies a corresponding analog manipulated variable (a SG ) to a driver circuit (2) which has a compensation current (I Comp ) to a coil (110), which is held by a rotatably mounted measuring lever (106) displaceable in a magnetic field, at its first end piece (106 c) to measuring force is introduced and at the second end piece (106b), the aperture is provided. Waage mit elektromagnetischer Kraftkompensation mit einem Ausleger (101a), von dem eine zu messende Kraft über eine Koppel (105) auf ein erstes Endstück (106c) eines drehbar gelagerten Messhebels (106) übertragbar ist, dessen zweites Endstück (106b) einerseits eine Spule (101) in einem Magnetfeld und andererseits eine Blende hält, durch die Licht von einer Lichtquelle (D3) zu zwei übereinander angeordneten Fotodioden (D1, D2) übertragbar ist, von denen je ein Fotostrom (I1; I2) als Führungsgrösse einer in einer Regeleinrichtung (10) vorgesehenen Differenzmessschaltung (1) insbesondere nach einem der Ansprüche 1 bis 11 zuführbar ist, von der eine dazu korrespondierende digitale Rückführgrösse (sPWM) erzeugbar ist, für die in einem Regler (RD) eine digitale Stellgrösse (dSG) berechenbar ist, die in einem D/A-Wandler (9) in eine dazu korrespondierende analoge Stellgrösse (aSG) wandelbar ist, für die in einer Treiberschaltung (2) ein dazu proportionaler Kompensationsstrom (Icomp) erzeugbar ist, welcher der Spule (110) zuführbar ist.A balance with electromagnetic force compensation with a cantilever (101a) from which a force to be measured can be transmitted via a coupling (105) to a first end piece (106c) of a rotatably mounted measuring lever (106) whose second end piece (106b) on the one hand has a coil ( 101) in a magnetic field and on the other hand holds a diaphragm, by the light from a light source (D3) to two superposed photodiodes (D1, D2) is transferable, each of which a photocurrent (I 1 , I 2 ) as a reference variable in one Control device (10) provided difference measuring circuit (1) can be supplied in particular according to one of claims 1 to 11, from which a corresponding digital feedback variable (s PWM ) can be generated for a controller (R D ) a digital manipulated variable (d SG ) can be calculated, which in a D / A converter (9) in a corresponding analog manipulated variable (a SG ) is convertible, for which in a driver circuit (2) to a proportional Kompen sationsstrom (I comp ) can be generated, which is the coil (110) can be fed. Waage nach Anspruch 12, dadurch gekennzeichnet, dass
der Regler (RD) ein Rechner ist, in dem ein Betriebsprogramm (8) implementiert ist, mittels dessen Messprozesse steuerbar sind, wobei die digitale Stellgrösse (dSG) unter Berücksichtigung des gesteuerten Messprozesses berechenbar ist.Scales according to claim 12, characterized in that
the controller (R D ) is a computer in which an operating program (8) is implemented, by means of which measuring processes can be controlled, wherein the digital manipulated variable (d SG ) can be calculated taking into account the controlled measuring process. Waage nach Anspruch 12 oder 13, dadurch gekennzeichnet, dass
der Regler (RD) mit Sensoren (4) verbunden ist, mittels denen Störgrössen (x) erfassbar sind und dass im Regler (RD) Subroutinen implementiert sind, mittels denen die digitale Stellgrösse (dSG) unter Berücksichtigung der Störgrössen (x) berechenbar ist.Balance according to claim 12 or 13, characterized in that
the controller (R D ) is connected to sensors (4) by means of which disturbances (x) can be detected and that subroutines are implemented in the controller (R D ) by means of which the digital manipulated variable (d SG ) is taken into account taking into account the disturbance variables (x) is calculable. Waage nach Anspruch 12, 13 oder 14, dadurch gekennzeichnet, dass
der Regler (RD) ein PID-Regler ist und einen entsprechend ausgestaltetes Regelglied aufweist.A balance according to claim 12, 13 or 14, characterized in that
the controller (R D ) is a PID controller and has a correspondingly designed control element.
EP16156026.3A 2016-02-17 2016-02-17 Difference measuring circuit and a weighing apparatus with force compensation Active EP3208582B1 (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
PL16156026T PL3208582T3 (en) 2016-02-17 2016-02-17 Difference measuring circuit and a weighing apparatus with force compensation
EP16156026.3A EP3208582B1 (en) 2016-02-17 2016-02-17 Difference measuring circuit and a weighing apparatus with force compensation
JP2017016818A JP6810624B2 (en) 2016-02-17 2017-02-01 Scale with differential measurement circuit and force compensation
US15/434,276 US10240968B2 (en) 2016-02-17 2017-02-16 Differential measurement circuit, and balance with force compensation
CN201710085300.8A CN107091676B (en) 2016-02-17 2017-02-17 Differential measuring circuit and balance with force compensation

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EP16156026.3A EP3208582B1 (en) 2016-02-17 2016-02-17 Difference measuring circuit and a weighing apparatus with force compensation

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EP3208582A1 true EP3208582A1 (en) 2017-08-23
EP3208582B1 EP3208582B1 (en) 2021-01-20

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EP (1) EP3208582B1 (en)
JP (1) JP6810624B2 (en)
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Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102016009098B4 (en) * 2016-07-27 2018-06-14 Fresenius Medical Care Deutschland Gmbh Apparatus and method for testing a weighing system of a blood treatment device
EP3607283B1 (en) * 2017-04-01 2022-03-02 Koninklijke Philips N.V. Sensing and control device and method for a weight measurement device
US11366004B2 (en) * 2018-07-18 2022-06-21 Mg 2—S.R.L. Electronic device for detecting the weight of capsules for pharmaceutical products
CN111964826B (en) * 2020-08-28 2021-05-18 电子科技大学 Calibration device and method for micro thruster test system
CN112729497A (en) * 2021-01-19 2021-04-30 湖北航鹏化学动力科技有限责任公司 Efficient medicament weighing method and device

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3727708A (en) 1971-12-20 1973-04-17 Acurex Corp Force balance weigh cell
DE2311676A1 (en) 1973-03-09 1974-09-26 Intermadox Ag DISPOSAL VOLTAGE CONVERTER
DE2742146A1 (en) * 1977-09-19 1979-03-22 Sartorius Werke Gmbh Electromagnetically compensating balance or dynamometer - has temp. sensitive resistor moving system to compensation position
JPS59231421A (en) * 1983-06-14 1984-12-26 Arutetsuku Kk Electronic automatic balance scale with drift compensation means
DE10153603A1 (en) 2001-11-02 2003-05-22 Mettler Toledo Gmbh Difference measurement circuit for a control device and scales with electromagnetic force compensation having such a control device, whereby the output of the difference measurement circuit is largely temperature independent
DE202012012781U1 (en) * 2012-03-13 2013-11-12 Sartorius Lab Instruments Gmbh & Co. Kg Integrating A / D converter

Family Cites Families (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3500109A (en) * 1966-09-12 1970-03-10 Yokogawa Electric Works Ltd Integrating analog-to-digital converter usable in digital voltmeters
JPS534791B2 (en) * 1972-03-01 1978-02-21
DE2722093C2 (en) * 1977-05-16 1979-02-15 Hartmut Dipl.-Phys. Dr. 6203 Hochheim Gruetzediek Weight and force measuring device
CH658516A5 (en) * 1982-08-20 1986-11-14 Mettler Instrumente Ag SCALE WITH ELECTROMAGNETIC POWER COMPENSATION.
CH660525B (en) * 1983-09-29 1987-04-30
CN2117596U (en) * 1992-03-24 1992-09-30 李小平 Electronic weighing apparatus with gravity compensation
JPH10160551A (en) * 1996-11-27 1998-06-19 Shimadzu Corp Electronic balance
ATE301281T1 (en) * 2002-03-18 2005-08-15 Mettler Toledo Gmbh FORCE MEASUREMENT CELL FOR A SCALE AND SCALE
DE50203820D1 (en) * 2002-03-18 2005-09-08 Mettler Toledo Gmbh Modular load cell for a balance and balance
DE10346741B3 (en) * 2003-10-08 2005-03-24 Mechaless Systems Gmbh Determining and/or evaluating differential optical signal involves regulating intensity radiated into measurement arrangement with control parameter generated from incoming light intensity at receiver measured relative to phase position
DE102005043820B4 (en) * 2005-09-13 2007-08-23 Wipotec Wiege- Und Positioniersysteme Gmbh Lever gear, in particular for a weighing sensor of a working according to the principle of electromagnetic force compensation balance
PL1898193T3 (en) * 2006-09-05 2016-11-30 Force measuring device and reference unit
PL2253944T3 (en) * 2009-05-20 2017-07-31 Mettler-Toledo Gmbh Controlled and/or regulated force measuring device
CN101762795B (en) * 2009-12-31 2013-01-23 上海舜宇海逸光电技术有限公司 Optical fiber magneto-optic detection system and method
EP2634543A1 (en) * 2012-02-29 2013-09-04 Mettler-Toledo AG Weighing cell operating on the principle of magnetic power compensation with optoelectronic position sensor

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3727708A (en) 1971-12-20 1973-04-17 Acurex Corp Force balance weigh cell
DE2311676A1 (en) 1973-03-09 1974-09-26 Intermadox Ag DISPOSAL VOLTAGE CONVERTER
DE2742146A1 (en) * 1977-09-19 1979-03-22 Sartorius Werke Gmbh Electromagnetically compensating balance or dynamometer - has temp. sensitive resistor moving system to compensation position
JPS59231421A (en) * 1983-06-14 1984-12-26 Arutetsuku Kk Electronic automatic balance scale with drift compensation means
DE10153603A1 (en) 2001-11-02 2003-05-22 Mettler Toledo Gmbh Difference measurement circuit for a control device and scales with electromagnetic force compensation having such a control device, whereby the output of the difference measurement circuit is largely temperature independent
DE202012012781U1 (en) * 2012-03-13 2013-11-12 Sartorius Lab Instruments Gmbh & Co. Kg Integrating A / D converter

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CN107091676B (en) 2021-03-19
JP6810624B2 (en) 2021-01-06
US10240968B2 (en) 2019-03-26
EP3208582B1 (en) 2021-01-20
PL3208582T3 (en) 2021-05-31
CN107091676A (en) 2017-08-25
US20170234720A1 (en) 2017-08-17
JP2017167124A (en) 2017-09-21

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